I know I shouldn't compare XIV to WoW, but one of the few things they did right was adding a mandatory mini tutorial instance for boosted characters before letting them out in the open, because they'd know the player in question wouldn't know even the basics of basics to how to use the class, let alone letting them queue for roulettes.

That said, there's playing the game casually and then there's literally not doing their job. If, say, a healer is not healing because they're too focused casting their single dps spell*, that's not casual, it's not even minimum effort, it's straight up not caring, and tbh that's not a behavior that should be condoned.

*and no, I don't mean the WHM that will let me drop to ~10% and use Bene, you know which ones I'm talking about.