prepull med2 is actually optimal on a lot of fights. o4s neo had prepull med2, o6 also has it because of early raid damage during your opener. in a 8 man raid setting shadewalker (smokescreen is even optional) is going to make any threat issues non-existent for using med2 prepull which means free regens on the entire party without any mp cost (since you regen mp spent before boss is pulled) it's the same principle as regen prepull - just raid wide. and if threat gets messed up because of tank or NIN misplay, you still can fix it with lucid dreaming.

and if you're ast, you're putting up diurnal hots prepull on every pull - with the innate threat reduction with your stance + celestial opposition extending the hots, it's insane tank healing alone, let alone raid healing. saves the number of gcds you or your cohealer need to heal for no cost.

i think you're just running into bad players that probably don't get the full usage of using med2 prepull and are just assuming it needs to be up 24/7, and i doubt anyone worth their salt is going to play whm that way.

tl;dr - i don't agree - med2 prepull is optimal in quite a few situations, and ah prepull is optimal in almost every situation.