Fair warning, this strikes a nerve for me, and I'm practically just writing my own OP (although I did read the actual OP).
The statement "you cannot loves others until you love yourself", and all of its paraphrasings, is one of the worst aphorisms I've ever known. Among my all time most hated, probably along with just world hypotheses and maybe a few others I'm not thinking of right now.
1: It makes no sense.
2: It is more harmful than helpful.
Let's break both of those down.
1.
The statement does not explain itself. You are supposed to just accept that it's true. But why? I cannot seem to connect A to B here. Loving others requires me to love myself because...? It is patently obvious that an individual's relationship with others, of any kind, whether it be feelings, or actions, or whatever, is not necessarily a mirror of their relationship to themselves. Hell, it probably usually isn't. I would think you only have to do cursory analysis of anyone else's relationships, or the history of your own, to know this is true. If it's not generally true, then some kind of reasoning must be given specific to love. Why does love always match one's attitude toward the self? If love if is a feeling, I don't see why that would hold. I'm pretty sure I've loved other people more than I've loved myself... hell, I'm pretty sure I've loved cats more than I love myself. Am I supposed to just take the word of someone who's never been in my head that I don't feel what I'm fairly confident I felt? Fuck that. There's no reason to give their word more credibility, and there is still no logical explanation here.
What if it's not a feeling but an action or a system of actions? That holds even less water because it's more demonstrably false. People constantly do for others what they do not do for themselves. It's practically the definition of being a parent. And if what we're boiling love down to actions, my idea of a loving action is a giving one, which is basically directed away from the ego by definition. If your idea of love is defined in terms of actions, and you think you have to love yourself to love other people, that basically means you'd never give anyone 5 bucks unless you first made sure you got 5 bucks and balanced out the loss. That sounds more like being a selfish prick than loving other people, to me. In other words, this would make you less loving toward other people.
So back to square one. Which part of loving other people operationally depends on some part of loving myself to already be in place?
2.
If put into practice, this formulation is almost perfectly designed to make people do the wrong thing.
First of all, it only hurts people who have low self-esteem. I think this is the main thing to OP is getting at. Suppose someone isn't feeling good about themselves, and you tell them that they are incapable of engaging in one of the most meaningful parts of life and something that tends to be deemed fundamentally good and even a measure of a what good person is. How is that supposed to work? You're basically going up to someone with a low self-esteem, and telling them, "hey, because of your low self-esteem, you're going to miss one of the most important parts of life, and you're a broken, kind of shitty person" You've just given them another reason to feel bad about themselves, and if you've made a death spiral, because you just told them to feel bad about feeling bad about themselves. Furthermore, that statement is entirely disempowering. It tells them what they can't do, doesn't tell them anything they can do. Which is the second thing.
This statement is devoid of useful suggestions. It's all about detailing how your affliction will ruin you, and nothing about how to treat the affliction. If a person has self-esteem problems, it's a pretty safe guess they aren't sure how to develop self-esteem. Perhaps you should try telling them how to do that, instead of idiotically telling they might want to do that. No shit. It's like saying "I really think you should stop being sick". I find most people who like to throw this wisdom around are kind of dry wells when it comes to suggestions for how to actually deal with low self-esteem itself, rendering them virtually useless.
So if you're keeping track, what we're doing so far, is telling a person who feels bad about themselves that feeling bad about themselves gives them even more reason to feel bad about themselves, though we cannot explain why, and we have no suggestions about how they should actually stop feeling bad about themselves.
Unfortunately that's all. It's also harmful in an entirely separate way. That's because this notion has a corollary (though, technically, not a logically necessary one, just an intuitive one apparently). The corollary is that, if someone is unloving, even hateful, it means they don't love themselves. And that means, getting someone to love themselves might be a solution to making them more loving. And this is a terrible, terrible idea. In the final sense, it basically means you should give emotional support to sociopaths. See someone being a dick? Make them feel good about themselves. This is what lead to the ludicrous, fuck-up of an idea that if you just automatically try inject everyone with self-esteem preemptively, you'll cut down failure and abuse. Start with kids, they'll get good grades and stop bullying. But it's never worked. And it's probably made everything worse.
The idea can also be self-servingly abused firsthand. If I have to love myself before I can love anyone else, then you're all on the back burner until I love myself. When will that be? As I've pointed out, nobody knows. It's not an operational idea. So, you can't tell me I'm wrong if I state that I'm still striving toward loving myself for an indefinite period of time. It could take the rest of my life. Fuck you, I can't love you yet, I'm still working on loving myself.
...
I'm almost done here, but let me just preempt some of the defense of the aphorism. There's a typical way I see it defended. That is to redefine love, and then re-redefine love, and then re-re-redefine love, etc.. until it has no meaning at all, and thus can mean anything you want it to mean, and the statement becomes unassailable. Unfortunately it also makes it useless in its meaninglessness. If this thread picks up steam and starts an argument, I'll be damned if that doesn't happen.
Also, if you've known people with low self-esteem, and you've told them this, and they don't like it, perhaps that's a clue that this isn't very good advice. You should take feedback from people you're trying to help. if you're really trying to help them. I often get the sense that people are far more invested in defending this idea or themselves for saying it than they are in helping in anyone. Like, for some reason I can't perceive, this is for them much more than it's for any of the unhappy people they are saying it to.
...
Okay. I could probably spend all day adding more and more criticism onto this, but I think I got the urge out of my system. I guess I'll wind it down with this last thought.
Chronically low self-esteem is exhausting. It's really exhausting to try helping someone with that problem, I'm aware of that from both sides of the relationship. So when it comes to counseling a person with low self-esteem, ask yourself these questions before you say or do anything.
Do I really want to do this?
Am I cutout for doing this effectively?
Can I afford to bother with doing this?
If the answer to any of those is no, just don't try to help. You and the person with the self-esteem problems will be better for it.
EDIT: Given the speed at which I typed this, it probably has more errors than I feel like dealing with right now. Sorry.