I don't think anyone is arguing that machine readable specs should take the place of human readable documentation. Specs are helpful for testing, integrations, and generating HTML docs.

I agree the API provider's primary concern should be Developer Experience, and understand why creating a spec often takes a back seat. But I suspect that soon it will be seen as critical for any production grade API to have a machine readable spec.

I view specs as analogous to unit tests - it doesn't get you closer to a deliverable product, but it makes the development lifecycle much less painful.