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.
It might be useful in some senses to realise that not everyone is the same. It gives a structure for people to understand difference within. ie. replace one misconception with another. But how is giving a person a type beneficial when understanding them? To benefit at all from the knowledge of a person's type one must generalise the characteristics of the type and apply them to the person. If the person has taken the test this is probably of benefit statistically (because you get them to privately tick boxes then guess which boxes they ticked from their four letter result), if the person has not taken a test I'm not sure it has any value at all. Someone who hasn't taken the test has been typed by studying their characteristics, hence you know those characteristics without typology, and any new characteristics you assume as a result of this typing are a generalisation based on the typing. I don't see any gain in knowledge, only an assumed one as part of the generalisation.
The only way I see MBTi as being beneficial is that it creates a game where we try to look at ourselves and others in more depth. You aren't really understanding types, you're understanding people.
Freude, schöner Götterfunken Tochter aus Elysium, Wir betreten feuertrunken, Himmlische, dein Heiligtum! Deine Zauber binden wieder Was die Mode streng geteilt; Alle Menschen werden Brüder, Wo dein sanfter Flügel weilt.