Reiner is 100% correct here, there is physically only so much healing uptime they can introduce before it overwhelms the average DF healer (and as we know that amount is quite low), for that region of healing could they make the healing aspect more engaging……yes, have they shown any ability to do that in 5 expansions beyond maaaaaaaaybe misery……..no.

Now even if they did fix the healing aspect there is still so much downtime in this game, what can they fill it with
-buffs - well they have deleted interesting buff actions beyond “make someone else’s damage go up” and the design of the two minute meta means any attempt at this will just end up like the trash fire that is EW AST
-debuffs - there is really only two types of debuffs in this game
1) enemy damage go down (aka mitigation)
2) enemy defence go down (aka party buff)
Neither of which you can build an engaging gameplay loop around without something like the boss simply being too strong if the healers don’t rotate 100% uptime debuffs which returns to the original problem of the average DF healer just not being that good
-damage - damage becomes the only logical conclusion to what to do in downtime because of the way square designs their own game and right now damage is boring as hell