Can Healers Stop Running Ahead in Dungeons

[Canadane]

Not saying all healers do this, but oh boy when they do they expect me to be able to tank 5 groups of mobs at once.

Yes that is a normal amount of groups.
Don't be a slow tank, keeping up with the groups a rather important part of the role.
As a tank main myself seeing slower tanks makes me want to encourage them and teach them that they can take much more at once.