Gregory's Server
It depends on who you ask, whom the problem hurts the most, and whether an *effective* non-technical "solution" has any chance of being found and *implemented*.
E.g., multiple harassment problems here have been solved for me by using the mute and block features of Mastodon. Requiring me to consider this "not a solution" until the Fediverse, society or whoever has *effectively* dealt with it would have persisted the problem indefinitely, for me.