That directly contradicts your previous comment (that RFCs are the contexts that the teams are supposed to evaluate). Either:
1: non-comprehensive discussions are appropriate for a RFC, and random forum threads are the wrong place for that, in which case your previous comment is absolutely correct that it's unnecessary and likely counterproductive for the crates.io team to weigh in on said threads, but that still leaves the question of why they [edit: the crates.io team] haven't made such a RFC [edit: and told people commenting on the forum threads to instead comment on the RFC, where the crates.io team can evaluate] yet.
Or:
2: non-comprehensive discussions are not appropriate for a RFC, and should take place elsewhere (ie random forum threads), in which case it's completely reasonable to expect normative (but obviously not binding) feedback on what would be necessary to produce a RFC-quality proposal in the first place.
Personally I weakly favor the former view, on the basis that RFC literally stands for "Requests For Comment", but either one would be a sensible position, as long as one doesn't try to assert the negation simultaneously.