It’s because you’re giving an absolute worst case scenario (people outright lying about everything about themselves in order to get in the other person’s pants) and presenting that as if it’s a universal truth for every person that ever goes on a date.

The reality isn’t so dark. Highlighting your good qualities while downplaying your bad ones is closer to a universal truth about dating, but that’s not the same thing as what you’re saying. What you’re saying sounds like people go on dates as characters they made up that are nothing at all like them.