My usual concern with force redirecting people to “where the stuff is popular” is that it promotes centralization, which is the literal opposite of why we’re here. Besides, as I’ve commented some other times, the feasibility of user participation is not transitive across instances. !soccer@sports.xyz might have a completely different rules, mood or culture than !soccer@euro.pe , or the redirect might lead to !soccer@ya.ml which is blocked in my country or otherwise made unavailable. (I am using examples here ofc but I guess this could very well hit people in and around feddit.uk, for one).

There is literally no punishment for keeping a community open so it can sometime either grow organically or die organically. Locking them however, fully prevents either option.