options:
A. Let them tank the things they pull. (not great cause they're either going to die or the healer will have to work overtime and then pull aggro and the whole run will just take longer)
B. Go as fast as you CAN.. and go pull the enemies off them. Silently resent them.
C. Ask them to stop doing that, politely. (many people in this game aren't aware of how frustrating this is but will gladly accommodate requests)
Some people are very focused on as fast as you humanly can and will pop sprints/teleports/movement boosts. They're welcome to play how they want.. but you are too.
All in all you're probably best off just trying to pull the mobs off them at your earliest convenience. They'll probably be able to weather at least a couple hits. Unless people start getting restless in chat just finish the run.