Do you need any evidence for this? Shouldn't this be handled in the same way you would patch a security hole even if you had no evidence it was being exploited?

I.e. shouldn't Reddit let a community exist, even if some users post content against the rules, as long as the moderators are putting a reasonable, good faith effort to ban such users?

(I don't know if what notadev said is true, or if Reddit bans communities just because users are posting bad content against the moderators will)