It was not “few” flags in this case. Far from it. Note the variables in the statement above:
new user X has Y flags outstanding by Z different TL3 users, time to auto-block them
Reluctance to cast flags is epidemic along all the Discourse sites I know of, and has been for a long time. Users simply don’t flag unless it’s severe. And of all the users who do cast flags, I’d trust TL3 users the most.
Anyway, staff can unblock users any time, so it’s not like the block is permanent. Bear in mind too, this would only work against new users.
