There's decent odds this is kind of a disconnect on your part from the vast majority of the frequent posters here, yeah. I suspect you probably play RPGs *far* more safely than the people you're typically arguing with.
To me, as someone with a lot of console and tabletop RPG experience, a healer isn't someone that strictly heals, but is the *go to option* for when healing is required. They're not healing every single little cut and scratch, but they have tools to rapidly patch people up once they're in danger of being punished by the next incoming bit of damage (by being KOd and taken out of the fight). A lot of games don't even have a ton of different healing options, just a couple of basic level ones, and maybe they scale up with levels, and the rest of the kit is devoted to other ways of supporting the party, What those other options tend to be can vary a lot from game to game, and especially class to class if there's ever more than one healer available, but generally they seem to be built on the assumption that they either spend a lot of time buffing or debuffing enemies as a way to serve as an indirect damage torq, or being able to do modest damage directly, with defensive de/buffs generally being something only pulled out for harder boss encounters. And you're doing these non-healing actions a lot, because monster typically aren't capable of outputting enough damage to burst people down to the ground in one round without them already being significantly low on HP, and healing between battles takes the same resources as in battle so it's a more efficient place to do it when possible. Rez effects are a safey net for when you've either misjudged a situation, or taken a gamble and lost, but either way it's a way to course correct after you've fucked up the most important part of your job (Everyone's HP > 0).
Even if you look as far back as one could reasonably go with D&D, they (Clerics) had limited access to healing tools, decent armor/weapon options, and some surprisingly good offensive spell options alongside a smattering of buffs and crowd control options (which often weren't in conflict with healing resources due different spell tiers and not having unified MP). And as D&D has been iterated on and remade, every single one of those points has been reinforced (other than maybe the armor/weapon thing, which is still an option but they've also gained the ability to be lightly armored and more ranged blaster-y rather than melee-y). I'd assume most of the frequent posters have similar understandings of healers, given the sorts of arguments they get into with you.
Fundamentally I don't think MMO healer expectations are really all that different, other than the assumption that you'll typically have a lot more buttons/skills at your disposal and perhaps more of an expectations for your HP fills bars to be varied and interesting, as well as having more liberal access to healing (as fights tend to be much longer, and kits balanced based on being more or less resource full for any given encounter, rather than the slow bleed of non-renewable resources over the course of a dungeon delve).