If your reaction to a bad pick-up party is to make things WORSE by deliberately sabotaging it, understand that you are part of the problem.

It's fine to speak up, explain to them what's bothering you, and ask them to change. There's no guarantee they'll listen (sometimes they CAN'T listen, if they don't speak your language), and that is their prerogative. You then have the choice of abandoning the run if you simply can't tolerate it, attempt to vote kick the individual on grounds of harassment, or just put up with it and continue to do your job.

The healer who lets a party member die to prove a point? The tank who lets a party member die to prove a point? The DPS who pulls extra mobs to prove a point? They make a bad situation worse - and more than that, more likely than not no point is actually getting through. The other party members don't know you're trying to play party police - they just think you're a bad player. And they are absolutely correct: someone who sabotages their own party IS a bad player.