DPS who pull mobs

[NanaWiloh]

It's like saying DPS shouldn't use Bloodbath or Second Wind because healing is not their job or that a healer shouldn't DPS because DPSing is not their job.
As long as it's not detrimental to the run there is no reason not to do something.
If a DPS runs ahead, it's not inherently detrimental if it's handled well, it's extra mitigation for the tank therefore less to heal for the healer.

But a tank or a healer letting people die out of petty grievance will never be beneficial, ever. Quite the opposite it's going to make it much more difficult because less damage means the pull will last longer and the tank and healer are at a much increased risk of running out of resources.

This is such a over used reason. Dps healing skills are weaker then a healers spells. And healer dmg skills are weaker then dps skills. So you cant take the roles place or what its capable of.