The objective bottom line is that those players can and should be reported and warned/suspended for their behavior.

"Not going fast enough" isn't grounds for kicking someone from the group. Obviously if the tank is just standing still and afking, that's grounds for kicking, but just taking it group by group is not valid grounds for kicking. That's harassment.

So those people were in the wrong. If they want to set the pace, they can play tank. A tank should only pull what they are comfortable with, regardless of "assurances" made. For all they knew, the tank was new or inexperienced and was still learning. In that case, what they did amounted to blatant bullying. Not acceptable.