This is a lot more accurate than people give it credit for.
I have several friends who main dps and haven't touched a healer in any MMO ever. Whenever they hopped into DF to do roulettes or something with me, they audibly panicked. Like a partywide from a dungeon boss hit, party at 60%, I glared away while waiting for Assize and they went like "Uhh... Elli? I dropped really low. Elli? Aren't you going to heal? I'm really low and ohmygodthebossiscastingsomethingI'mgoingtodiiieee" and whenever we exchanged DF stories, they praised the random healer if they were always topped. "He was really good, I didn't even drop from the aoe because they preshielded the whole party before every aoe" "The aoe barely hit and I was already topped, that was a really good healer" and so on.
One of them did dabble into healing lately and he behaved exactly as he imagined healers to be when coming from a pure DPS main perspective with the vague idea about what healers do: he was topping people off all the time, shielding them for good measure when he was done topping them off, sprinkling a few dps casts but the moment damage hits it was healing to full into shielding everyone again right away. He treated GCDs as bread and butter and oGCDs to "support" GCD healing during high damage phases. And high damage phase was something like the party dropping to 50% once and nothing happening for the next 20s+.
He couldn't, for the life of him, wrap his head around the idea that healers can heal most content with oGCDs alone. When I told him I usually don't touch GCD heals outside prog (or if things go really, really wrong) he was genuinly surprised because he used them so frequently so he couldn't imagine healing an Extreme, let alone Savage boss, with oGCDs alone. It sounded completely impossible for him, he was sure the whole party would die after 2min tops.
He openly said that anything below 80% is a no-go for him and if a healer frequently lets the party drop this low, he considers them bad and not comm them and that "empty" (=below 70%) HP bars make him anxious because his job is top to top off first, prepare for the next damage next and lastly maybe sprinkle in a dot or a nuke here and there.
The HP bar anxiety was almost hilarious.
I know it's just anecdotal but I can well imagine where they're coming from if they never played healer or only briefly tried it to have one healer maxed. This is how pretty much every DPS main I ever met that tries healer for a bit played them. Top party off. Shield if you can once topped.