... but actually, no apology necessary. I just wanted to understand why they do it.
It's a matter of dealing with people, and actually, now, if we look at it, some strategies if overused can actually created hardship for the person and the other people they deal with. It's not like NTs shouldn't apologize in some situations, when it makes sense and is actually beneficial to everyone; meanwhile, NFs don't need to apologize for everything.
It has nothing to do with a judgment over "what a type should be," it's about doing what is most beneficial in a given situation.
... but... then again.. people are who they are. So.... now what?