I accept whoever requests me because if my gameplay and attitude is something that makes you want to play with me, then chances are you're a decent enough person and like the positive vibe I give off, or maybe just enjoy not getting berated by your ADC for mistakes you know you made. So yeah, I'll just accept everybody for the most part. But some people just add people after a game and swear at and berate people because of some perceived slight against them, and possibly challenge to a 1v1 to assuage their ego.
I've also gotten some who were saying rude things in game but request me and apologize as well, though.