The main difference with PR review is that code is tangible and real and carries more weight than a document full of plans and ideas. There is a broader acknowledgement of the cost of changing working code, but that price-sensitivity seems to evaporate when it comes to RFCs.

Again, I think you are assigning too much importance to comments/questions in the RFC. Yes, there is probably an expectation that a comment/question is _acknowledged_, but I disagree there should be an expectation that it is _resolved_. The same as a PR.

If in a PR I left the comment that 'This architecture binds us to AWS. Have we estimated the engineering effort to remain cloud-agnostic in case we need to move to Azure next year?", it would be bad form for you to ignore the question and merge. It would be totally acceptable to either say "no, I didnt take that into account and I think its out of scope" or "yes, and that will be tackled separately". And it should always come with a consideration that there might need to be more information added to the PR, eg adding clarifying comments to the code.

If you're making a proposal, I feel like an RFC carries a lot more weight than a slideshow or an email. If you really don't need feedback or approval from anyone, sure, go it alone. But if you do need or want to run it past someone, let the document you send them reflect the amount of thought you've put into it, and then maybe they'll hesitate before going off half-cocked & suggesting some idea you already considered.