@aljoscha lots of problems spin out of that... like, if each peer can choose XXX limit, then what happens if the peer you are replicating has chosen a different one and you don't have that? if there is a fixed limit... then how is that different to the current set up with 8k messages and blobs?

Wether something like searchable blobs becomes "part of the protocol" depends on how many applications use it, and whether it's considered indispensable. To answer that question, we need to experiment - and the nice thing about that particular experiment is that it doesn't mean changing anything that already exists.