Either that or charging a micro transaction for loading the page. But yeah the goal is to make it cost a small amount that is insignificant to a regular user but adds up to a huge amount at the scale of a spam farm. And it’s also the same rationale behind hashing passwords with multiple rounds. It adds a tiny lag when you log in correctly but adds an insane amount of work if you’re checking every phrase in a password cracking dictionary using an offline attack because it adds up. (In the online scenario you just block them after a few attempts)
At least with radicle all the forks will still exist even if the authoritative copy is taken down. And even then I think because radicle is like BitTorrent, anybody who pinned the main repo would still be seeding it so it would be very hard to scrub it completely. The main challenge in using radicle is getting an active contributor with some reputation to maintain their copy on there. Otherwise there’s no momentum and nobody will pin the countless mirrors published by randos.