The thing is, you can't force people out of your party unless you PF your duty roulettes. Most people would still rather take the convenience of queueing up in DF.
And if someone decides to kick an unoptimal player? Well, they can get reported for unjustified usage of the vote dismiss system after a GM reviews what's happening and sees that everyone is playing as normal. I don't think any normal person is willing to risk the account they've built on for years just to clear their expert roulette 2 minutes quicker.
As for people being toxic to each other, nothing anyone can do will ever make that go away. You could design a game where all you do is hold hands and skip through flowers and someone will kick you for not taking the speedrun route.