My feeling is that it isn’t the case that everyone is limited to the lowest fps of anyone in the game. I can’t recall ever seeing anything that can definitively prove that it’s not the case (we’d need to see a game that is being streamed by multiple players at the same time, and see one of them running at low fps but not the other), but I think what I’ve seen makes it unlikely to be the case. For example, TheViper clearly runs the game on good hardware that maintains high fps even late in busy multiplayer games, and if he were limited to the lowest fps of anyone in the same game, you’d think he’d encounter another player every now and then who causes his frame rate to be low, but I’ve never seen that happen.
So my feeling is that a poorly performing PC mainly only hurts the player who is using it, but obviously it will also hurt their allies in a team game if their hardware means they can’t play as well.
I’d say 1000 benchmark score isn’t really enough for a busy 4v4 late game, and you probably ideally want more like >1150, but if it only causes a problem for that one player, I think it’s reasonable to leave people to choose for themselves. If it reduces their performance in team games, their team ELO will match that lower performance level.