What do you guys think is the cause of severe lack of Tank users?

[Kabooa]

If one is refusing to fix or compensate for bad play and thereby make the run more efficient just because they might get smeared a bit, too, if the tank especially poops the bed, isn't that exactly the excessive fear over etiquette that Sam was talking about?

Kinda. It's hardly perfect, and in dungeons specifically it doesn't usually work because, ironically, an individual player has significantly more potential to actually make a difference for one of those decisions.

In my experience, I lose more time trying to correct course than I do letting them do what they want, as there's less fall back, less talking, and less rage quitting.