Why do…

[Duik]

Just my 2cp
Im old but originally in groups the high burst dps (wiz for example) would wait till x% damage was done. To ensure (hope?) agro was stable.
Now, after 20+ years of poopsockers poopsocking and finding infinitesimally small gains everywhere (IMHO wrecking the spirit of the game but nvm that) along with some unbalancing twinks (medium ones which are ok by me. Sue me!) that are ridiculous (eg. de-levelled epic rog etc) means melee dps like these bad boys easily out taunt even well played tanks.
XP groups of this type generally destroy content fast enough to mitigate any mob swapping. Well/over equipped (monks especially) twinked melee also tend to be able to absorb more damage.

So all those things added together mean very few need to await the tank gaining agro like us in january 2000 who had zero clue (and loved it!) about rooting and proximity agro and which innocuous (seeming) spells would peel a mob from da tank. Snare, debuffs and dots.