We all know the current 5 man dungeons. We all know the extreme queue times as a DPS for random queue. We all know how incredibly fast your M+ group gets flooded with DPS applicants and you can choose your prime rib with too high itemlevel.
It's obvious why, the vast majority of gamers want to play DPS. Be it because being a healer is annoying where everyone blames you every time they die or you running out of mana, or as a tank you have to know the dungeon inside out and pull perfectly else you are a moron. It could also simply be because the vast majority of the specs in the game are DPS.
Overwatch 2 made a big change where they changed the game from being "2 tanks 2 healers 2 dps" to be "1 tank 2 healers 2 dps". People simply don't enjoy playing the main tank shielders like Reinhart or Orissa as much.
More DPS means better queue times for the role. It also is a better representation of a raid composition where the DPS to tank ratio is not 3 to 1.
Should WoW change to be maybe 1 tank 1 healer 5 DPS? What problems would that cause?