That is a misconception about Akku. R6RS and R7RS libraries are
self-describing, so Akku does not require any particular repository
layout. You just need to use any of the common file extensions: .scm,
.sls, .sld, and so on. You can run "akku scan" in a repository to verify
what libraries it finds. Most packages that are published to akkuscm.org
actually come from git repositories that were not prepared whatsoever
for Akku.
Even if Akku can work around it, Marc's making the point that not having to make a separate choice for every single SRFI is beneficial itself, and that we should therefore adopt a convention.