I don't think it is at all unreasonable that someone coming into a class labelled as "Healer" in a Heal/Tank/DPS trinity game would expect healing to be their primary and overriding role.
Sure depending on the exact class in the exact game you’re playing you might expect to DPS, Crowd Control (if that's a thing in a given game), use some kind of active buff system or do any number of things in addition to healing. However you could not at all be faulted for assuming those things would be secondary considerations to healing. In addition since the game has you levelling from 30 to 60 as usually the only healer in the group this further trains you into thinking of your self as first and foremost a healer, anything else a distant second. Sure with gear and experience you can learn how to offload to the fairy with a shield or two in the mix once even outside the newbie dungeons, but that probably means this isn't your first pass as a healer.
Then you get to the end game and it's not just you and the fairy healing, plus whatever you can fit in on the side. It's the fairy healing, you DPSing, shielding specific attacks and healing on the side when you have room for it... or so I've read.
I started with healing in this game with SCH because the pet was a novel concept and I love shielding mechanics. However when I decided I wanted to move into the endgame eventually the only thing I heard was stories exactly like the what the OP has put forward. "90% DPS", "You know you're doing your job right when you need to cast heals as little as possible", "My goal is to stay in cleric's stance as long as possible". Not something I wanted to test out by diving in the deep end on. I started levelling AST so I could actually be in a healing role once I start endgame, because that's my preferred role in games. This is in spite of really quite enjoying scholar and the depth and flexibility of the toolkit I've found with it so far.
This isn't to say that a DPS class with some mitigation tricks, that can also function to help carry healing during high pressure situations is a bad thing. However, it is certainly fair that someone might be a bit off put by it when they signed up to be a healer, green party icon and everything and were a healer-with-other-stuff-on-the-side throughout their entire levelling and pre-savage gearing experience.
If this isn't the case and Scholar does first and foremost dedicate most of their time and energy to healing, then the community is very poor at communicating this and is certainly able to push new prospects away from the class. At least from the point where you're standing at the end of your experience with levelling and roulettes about to dive into deep content, it looks like the game pulled the ol' bait and switch on you.