I'll never forget a little experiment I did back in Heavensward. If my co-healer didn't turn on Cleric Stance within 20-30 seconds, I left them to solo heal the entire fight. A few exceptions were if I got paired with a new healer or it became clear they simply couldn't handle it. I didn't want to outright cause a wipe if I could step in and save the run.
The sheer amount of "sylphies" who were utterly clueless at how to actually heal was staggering. And this wasn't in Savage or even EX. Just normal mode Creator, 24 mans and the like. I had one person mouth off in chat, "Cassandra in her PvP gear just wants to DPS" after they ran out of MP (remember when that was a thing?) in the first phase of A12N because they literally spammed Medica II for everything. Fortunately, the DRK in that party called them out. Even nowadays, some eight years later and I get the "healer mains" upset I'm not healing enough. Had a healer in P11S ask if I'm "barsing" after she, the White Mage died to the raid just before everyone runs north. First, I had my oGCDs up and nobody else died. Secondly... when I looked at the logs, I noticed Assize was drifted all over the place. Guess what would have been up where she died if she pressed it properly?