On Levi, and this happens as well. The thing is, the majority of the people who have done the primals can't really be bothered to go back and do them again. There is little incentive to do them more than once as Levi drops a higher level weapon anyway and is farrr easier to farm compared to any other primal (except maybe king mog, but that's more of a tank check). The items they drop aren't necessary in most cases, and not a lot of people care about the mounts or have them already. I've done them a few times each, but don't really want to anymore aside from maybe solo tank Garuda since that is quick and painless (usually).

YMMV