fyi I have made some notes on previous RFCs that seemed to be well
received in general but then didn't actually get approved.
The aim of these notes is to make it easier for people to see what
happened to those previous RFCs and what hurdles they might need to
overcome, if and when someone wants to revisit them.
I'm planning to keep adding notes about the RFCs that seem more
important to me, but not to be a comprehensive list.