There's an saying that goes something like 'my right to swing my fist ends at the other man's nose' I like to translate to things like this.

Yes, you pay your own sub, you 'can' play however you like. But when 'playing how you want' translates to negatively impacting the group, you lose that right. Whether that means you're causing wipes directly or just not pulling your weight. You have a right to play how you want. You do not have a right to only do single target dps in a dungeon where the rest of the group is doing big pulls and aoeing. You do not have a right to play 'frost mage' though I don't think I've ever actually seen one of these in person. You do not have a right to put no effort into avoiding aoes or obeying mechanics. You can do these things but if you do, people are justified when they get frustrated with you or vote kick you from the duty.

I don't demand perfection. I'm not a perfect player either. I make mistakes. But I also try to learn from them. If I find out I'm not doing the rotation right on a job, I try to improve. If I find out I'm doing a mechanic wrong, I try to fix that.

That said, this doesn't mean the first recourse should be calling someone bad or yelling at them. Try offering friendly, constructive advice first. But if said advice is ignored or they get definsive, that goes out the window.