I’m not sure what duniverse is, but I see other reasons not to have a monolithic repo. Monolithic repos are intimidating: there’s a lot to learn about interleaving parts, just like every company’s codebase. And there’s one big difference between a company and open source: in a company, you’re paid to learn to use the codebase. That incentive doesn’t exist in open source, and it’s really important IMO to keep things as small and simple as possible so that people can feel they can jump in (assuming the project really is relatively small and simple).
At the same time, companies have other incentive structures that don’t match up with open source. It’s really important for the employee to be visible to everyone else – working in a small repo ‘behind the scenes’ doesn’t demonstrate that you’ve been actively contributing to the company, and this is far less of an incentive for open source projects, where it’s more about contributing because you want something particular to improve.
To me, it seems that having the one organization housing different projects is sufficient. It would of course be great to refactor the codebases to use common libraries, and to convert all the projects to use dune, but the cost of having an intimidating massive codebase seems not worth it.