In reply to Ron.

You get it wrong, the sad thing is that this information is still cluttering the post table while very few people even know about this feature (do themes outside of the repository actually support it at all?). 12 years of "decisions, not options" and no one thought about making this feature a plugin and getting it out of core.

result: rest api will take more time because there needs to be a feature parity between what it can do and what you can do in the admin, so the developers have to spend more time implementing it :(