And it's pretty rare to find a healer that doesn't dps. It's also not uncommon to find especially co-healers that don't heal and only dps.
I'm not arguing against using them, it's more a comment on how this debate has raged, frequently, since about 2013.
I don't play healer hardly at all as I'm not very good at it truth be told, as a tank though I love a healer that spams holy like it's going out of fashion. That said if a fight is dragging on too long it's the DPS I look at, not the healer. Healer DPS is a nice added bonus especially while tanks are as OP as they are right now so it's great when a healer put in some numbers but I don't sweat about it if they don't.
For newer content especially where not everyone's geared yet, the tank should be pushing your healing intensity a little with big pulls. With a lot of dungeons there's usually that turn or alleyway of pulls especially where you should save bene just in case the tempo is off. Once people are actually geared enough, I really only use Bene as a last second "oh no I may have dps'd a little too much".
I'm safe enough with my healing though that I can dangle a tanks life and focus on DPS though. For the whole healer DPS thing, I can't say I ever cared as a non-healer if the healer themselves are DPSing or not. Some people are either not that good, get too anxious to multi-task, or netflixing after their 10th dungeon for the day. It's really whatever. The extra 5 minutes is not going to pop a blood vessel. Probably a big reason someone like me can last a decade here and these more... intense about the subject only last a few months or a year.
No you're completely right. There's some level of high cool downs and people not using them for obscure reasoning that they might have to save them for later. Cant tell you how many times I never used my 2hour in FFXI simply because it had a 2 hour cooldown and I "might need it later" despite planning to logoff for the night in 30 min XD
So which is it? That we can use ACT but not lord it over people or you flat out just can't use it. Because I swear I've seen both arguments a thousand times over on the forums and in game.