If their identities were to be revealed, it wouldn't be very hard to trace them back to their place of living, a kind report to the local police station would warrant enough intimidation to stop them. It is an extreme options, I concur, however, if that's what must be done. DDoS'ing is a crime everywhere in the world.
Doxxing someone is bad, I agree, however if they're willing to do this to a small community like LFS for years, it's pretty deserved IMO.