I think having an ID cert would probably be hard to do, and maybe also be counter productive. The field is so wide… I’ve always thought the flexibility of ID is it’s biggest strength. Standardizing skills for certification purposes would take some of that away, and potentially skew the perception of the field/people.
At least the title still mostly fits though. In the world of UX the name game is getting silly. I’m finding that a lot of the work is now being called UX/UI, and is really just UI styling. UX is (at least from it’s origins) supposed to be more of the research and information architecture side, but it seems like that’s harder to sell to clients and C suite than some pretty brochure-ware. …still, the name UX is popular. 