Why? It's one of two parties deciding that the round is a lost cause and seeing if the other party is willing to let RNG sort things out.
Nobody has to accept RPS
RPS lasts like 5 seconds at most and ends the round
It's not being friendly at all, since the loser dies
Not really even sure what you mean by "hiding behind RPS" either. Like I said before, nobody has to accept RPS, and if the person who proposed the RPS complains tell them to stop whining and move on with your life.
EDIT: Since you ninja'd me with that "people who disapprove of this post support breaking the final two rules, let me tell you why that's wrong. I'm not gonna sugar coat it and say "I disagree with it" since you worded it somewhat meanly, it's just straight up wrong.
1) RPS is not friendly, like I said prior, because the loser dies. It's ultimately just a way to end a round.
2) RPS can actually be faster than watching a Hale chase a scout for the next 5 minutes.
3) RPS is very short, I can't possibly understand why RPS is so annoying and unbearable to sit through for you.