It's a fair point and myself have had no trouble healing or killing anything so far in Shadowbringers, it's completely functional and probably more powerful than ever. The giant pickle I have to pick with 5.0 Scholar is that it's boring, uninteresting and just not fun to play anymore. In short: The pruning and combining of a lot of offensive flexible skills and dots, removal of Arcanist tools, even weaker and less impactful fairy and no tandem potential, introduction of powerful skills on long cooldown and the removal Cleric stance among others. There's a lot in each of these points for as they we been gradually removed and replaced over the course of two expansions.
I can hopefully answer that because I loved 3.0's Miasma II. It had a very weak initial hit, then around 90% of it's damage ticked in the dots it spread, it was also melee so you had to leave the safe comfort of a ranged position to use it. When Miasma II returned in 4.0 I was really happy, but there was something strange going on. Instead of having the inital hit/dot ratio being around 10/90, it was now 50/50, or 100/100 potency. Found this incredibly weird as I started just spamming this since there was so little else going on in huge packs. Then when 5.0 hit I realized why it was so weird: It was the second stage of evolution of SE's trademark "Fillerspell" and as it's third form it blossomed into Art of War until I read it's description before it withered into something so polished, bland, unimaginative and started to smell.
Saw this same thing on Paladin with Total Eclipse in 4.0. Not only did this made me think SE was fully aware people just pulled wall to wall in dungeons for aoe, but now fully endorsed it by adding one button to press over and over and over and over and over. That too evovled in 5.0 and now they have TWO buttons to spam press in huge pulls. PLD, almost like SCH, stood out for me as instead of having damage-based aoe emnity skill like war and drk they had Flash, a non-damage skill with Blind debuff. It meant having to find other ways of dealing damage in lieu of an aoe skill, which I found it made up for with it's impressive array of cooldowns and tools right at it's fingertips. But like with SCH, it got the SE treatment, it's got offence for days and now Cover costs 50 gauge for seemingly no other reason than to justify having a gauge among other things. But Im going on a tangent.
Miamsa II 3.0 was great because it was one of the Little Ones, temporary nickname for all the lost SCH skills, and like the rest of the Little Ones wasn't great on it's own. It was when they came togethere it worked so fantastically. Miasma II 3.0 was great because it wasn't spammable, you had better things to do than stand in melee and press one button over and over again. Unlike now, where Broil III and Art of War are the most used buttons on my Scholar.
This is something that already exists in the game, in the upper tiers of Palace of the Dead and Heaven on High you got mobs that hit hard, do random patrols and often have a deadly aoe or mechanic you have to deal with because you can't kill them fast enough. And pulling more than one is risky. Add in random traps, rewards and a one hour timer and you need to do running decision about slowly pulling and killing mobs in safe areas to open the portal or run past mobs hoping they don't turn around at the wrong moment. It's really fun, but you need to put in 3-4 hours to get there. Been wishing for a long time they introduce something like it inbetween MSQ dungeons and Extreme/Savage. 4-man content with hypertuned mobs, random elements and copious amount of loot. Because tense moments as you hug the wall to avoid a roaming chimera juxtaposed with standing outside the Deep Dungeon going through looted sacks is the kind of relaxing downtime I find is sorely missing from this game's fast-paced dailiy tomestone roulettes.