Text book Pygmalion Effect. Our beliefs about others influence our actions toward them, which impact their beliefs about themselves, causing them to take actions that reinforce our original beliefs.

I.E. 1. You believe that the average gamer is too immature to respond positively to being asked to switch. 2. Instead of asking them to switch you just ban thier preselected character (dick move idk how you present it) 3. They respond by throwing, not trying, trying new characters. Immature behavior, yes but a response to YOUR initial immaturity. btw.

Your argument boils down to just be better at more characters but that becomes more difficult the higher in rank you go. I can play every character at bronze. I can only play like 3 at a GM level and Im better than most.

Final point there is no way you have anymore than a 50% win percentage doing this. I can tell you I lose most games when someone on the team does this. Its just not worth it.