For better or worse, some people really want to hear your "We're the X for Y". My startup [1] isn't the X for any Y (the closest thing I've found is "we're the Dolby for reading" — but this is not a close fit and makes people think too hard), but I've heard from many mentors/investors that I should try hard to come up with an "X for Y" comparison because they and their colleagues like to hear them.
I agree with you that these summaries are sometimes quite awful, but in some cases they are quite apt. The conclusion I've come to is that if a very good analogy exists, you should use it. But the bar for "very good" should be quite high, since a bad "X for Y" will do more harm than good. You end up in meta-conversations about the analogy itself, which isn't helpful.