I mean... yes... healers should focus on healing.
That doesn't mean they shouldn't dps when there is no need to heal.
Unless of course, you just want to do nothing but heal, I'm sure that is dead engaging and will really enthrall all the healers.
In my mind, having anything more than 60% healing uptime requirements is setting a dangerous precedent. Even a death to a DPS would start causing wipes more often due to the healer needing to raise at times they're required to heal.
It would be interesting if there was someone who could analyse the number of button presses for each of their skills within an instance, followed by total cast time, followed by total time not casting. Apologies if this exists somewhere, I'm a ps4 player and not savvy to 3rd party programs that feed on game data
