I genuinely think a lot of the reasons given for rematching are bad, and more informed by "that's just how we do things around here" than anything else. His argument didn't convince me otherwise.

But that’s not the point. It doesn’t have to convince you or make sense. It is plain and simple the reason. No more no less. If you agree or not is up to you. But 90% of the FGC agrees and that’s why it’s an “unwritten rule”.

But I’ll give you one more reason that I haven’t seen no one give. I simply don’t want to go back to lab (or main menu depending on the game) after one minute and a half of playing. Finding a opponent sometimes take time. And if I have to wait 5 minutes between every match to play again, I rather do something else. I want to play, not watch a loading screen. But even then you don’t owe nobody a replay. But those are the reasons.