Looks like vectorizing over NamedTuples is explicitly disallowed. Probably you can still vectorize things over the keys and values separately, along with some helper functions, but it is a bit annoying. Looks like the reason was due to questions on whether iteration should be over values or pairs.
Indeed, that is precisely the decision that must be made. Neither one is obviously correct. And once a decision is made and goes into a release, it cannot be unmade — we all have to live with it forever.
