the question really is why are they stopping the pull if they havnt hit a wall.!?

even all the new dungeons are easy to tank everything so unless your healer is inexperienced you can literally just pull to a wall.

now speaking from a dps side of things its annoying because your holding buffs til your sure the tank has stopped and if they take of right after you use them then the buff will most likely be wasted or youll get cancelled casts missed attacks cus mobs are pulled out of range.

healer side, partly much the same you use a buff that helps you dps / heal more efficiently and then tanks runs of which means they put themselves in a position where they could be in jeopardy especially if healer didnt realize which could just force the healer to heal spam and not dps which means slower kills.

tank side of thinks, you wont have cd's available cus you might of just used it, dps buffs wont be as effective or available for each pull because of mini pulls. about the only real benefit would be wasting time for a cd to recharge to pull the rest at the cost of the groups total cd's.

in short unless you know you cant survive there is no point in this tactic as it just costs the group to much. so other than being new and not knowing the dungeon its kinda pointless and a waste of time.