Because you're both claiming to understand the failing of reddit's UI and claiming the same UI as a reliable indicator of all comments getting deleted. Rather, it seems some comments were likely missed because of the shitty UI. Relying on reddit's UI for this is the specific user error to which I was referring. I hope that's clearer.
Thanks for clarifying. I understand the failing of Reddit’s UI from reading about it in the replies here. I didn’t know about it when I first posted, so there is no contradiction there. I also had no reason then to believe that either the redact tool (which reported deleting all comments) nor the Reddit UX (which reported no comment left) were inaccurate in their reporting.
Had either displayed wording similar to that service page you linked to, I would agree with you that it would have been user error to ignore it.
Barring that, I think it’s a stretch to claim user error when an obscure technical limitation of Reddit makes its UX misleading in a non-obvious way.