Both, depending on how much yeu emphasize it.
If yeu put iron faith in it as being absolutely accurate to all individuals without deviation, then yeah, yeu're going to have major problems. People will invariably drift outside its' boundries, do the opposite of whot it claims they should, and so on. Obviously, we're not just 16 clones with no differences past that point. Cultural differences, gender issues, various neurological disorders, etc, etc, can all affect a person's overall behaviour.
As such, if yeu use it as a LOOSE GUIDE, and just as a vague generalization, a base to work from in understanding why people do whot they do... just a starting point, rather than the whole person, then yes, it can help considerably. I get along with my BF much better due to understanding how he thinks a little better; there's differences from how MBTI describes his type, as there is in everyone, but it gives a good enough basic understanding that it's easier to accept and comprehend why he does some of the things he does, which would otherwise just be "well I wouldn't've done that... I don't get it". Instead, I can look at it and go "Oh, well he thinks in this manner, so I suppose it makes sense that he would come to that conclusion, even if I came to a different one". Understanding, allows for far more tolerance to things that are different to us.
There are those who would abuse such, like those who refuse to associate AT ALL with people of a certain type, or employers who only hire certain types because they prefer them. These practices are silly, and completely negate human individuality.
Don't put much faith in victor's rantings; he tends to assume everyone will abuse it and take it as 100% face value and strictly absolute fact.
If yeu use it as a loose guide/starting point for understanding, as it should be, rather than a strictly enforced set of laws with no deviation, it can be quite beneficial. Just don't run off the end of the world with it is all, or it'll be more hazardous than were yeu to not have used it at all.