What I don't get is...

If "differing playstyles" is a valid reason to kick someone from a group, why then is someone who voluntarily chooses to remove themselves from a group due to differing playstyles penalized for doing so? If someone realizes that they aren't meshing with a party (for example, three people want a speed run and one person doesn't), it's far better that they take the mature route of simply excusing themselves from the situation and trying to find a group that matches what they're looking for than it is for them to stay and try to sabotage the run/get themselves kicked or conveniently "DC." And I don't think they should be punished for doing so because they didn't do anything wrong; they simply happened to be matched with a group who had a different playstyle.

I'm willing to bet there'd be a lot less need for votekick and a lot less bad behavior in general if people were allowed to leave situations in which they were unhappy without being punished for it.