@Danskermand
As I recommended in a previous thread, if you want to leave often, play pubs.
You're not supposed to play casually with comp, though everyone can do their own thing.
Though this is supposed to deter leavers, you are messing up both your teammates and the match.
(The match due to players not being able to get an extra kill or the match becoming unbalanced due to a certain player being put in the lobby to balance the match as a whole)
If you want to play competitive in this way, that's fine, but I find it unlikely for the devs to adjust the game around a group that doesn't really play the game as intended.
You see, just deducting RP won't really work against them, if they don't care about their rank then this kind of punishment won't work.
That's why they added the time penalty, which seems to be working fine otherwise you wouldn't have an issue with this.
And whilst removing this feature seems like it could help for players that are being harassed, it could also backfire with players mass leaving and causing issues for the entire playerbase.
Well, you do have the tools available to mute players, so I personally also think you can resolve a big part of this issue with the things you've already got.