Less visibility for those not already on it looking to join in too though. If it gets forced so far underground that law enforcement can't figure out a way in I don't see how some disaffected youth somewhere could either.

Having it out in the open also attracts the users in the first place.

Yes, but 8ch users have been expecting this since Christchurch, and in any case chan culture has a long history of people on one site raiding an other and causing it to collapse with DDOS or contraband or whatever. It's not hard for people who regularly monitor it to figure out where people will move to.