i would think it is because of push to start with.
alot of todays raids have directional, or multi direction AE's that need to have the mob either cornered, or turned at certain times to avoid them.
because of the above, and raid leaders bad experiences, at times i could see where they would rather just do away with the issue, then address it.
pet hold is a must, and using your pet corectly is a must as well. the pet user must constanly re position themself, call the pet off, then re send them on the corect side of the mob.
thats what makes it tough, the pet attacks from the side there master was on at the time of sending. so as long as the pet class is on there toes, pets shouldn't be a problem. it is the pet users that just "fire and forget" that can give pets a bad name.
this is a guild issue you should take up with all pet users in your guild.