I would like to believe so. Some vendors still exist though, with not so clean tanks.When I buy aquacultured coral frags from any well-known vendor, I just assume that the frags are pest-free as the vendor has such a huge financial incentive to keep pests out of their systems - well, at least pests that damage corals. So far that belief seems to have stood up. Have others found this not to be the case?
Given that, it would seem to be a low risk thing for the vendor to offer such a guarantee.
There are vendors out there that QT their coral but most only inspect and ensure no coral pest/ nuisances are present, rather than fish parasites
Honestly speaking, fish parasites have never scared me, granted I’ve never had a fish die (knock on wood) , even if one were to die, I doubt all will