Version management is a fallacy as far as benefits of mono vs poly repos. You can do one way or another either way. You can have 1 version of everything in poly repos or you can have mixed versions in monorepos.
We follow an eventually consistent model. That is, we strive to have 1 version of dependencies for everything, but allow temporary deviation. Sometimes those deviations are less temporary, but usually for reasons that would have prevented upgrades altogether for everyone if we enforced a single version for everything.
The main benefits are around ownership (people can do whatever the hell they want to their repos) and tooling/scaling (whatever works for your tiny personal project will work for any of our apps without needing to scale them). Those are separate benefits from monolith app to micro apps (because again, you can do either with either model). You also have some minor benefits that would be easy to work around but are nice to get for free (eg: Github's default history is actually useful in the web UI)
The only tooling you need to manage poly repos is something to do pull requests at scale when something needs to happen everywhere. You can everything else (eg: build management scoped to individual projects) basically for free, you can always clone the entire repo without issues, etc etc etc.
We follow an eventually consistent model. That is, we strive to have 1 version of dependencies for everything, but allow temporary deviation. Sometimes those deviations are less temporary, but usually for reasons that would have prevented upgrades altogether for everyone if we enforced a single version for everything.
The main benefits are around ownership (people can do whatever the hell they want to their repos) and tooling/scaling (whatever works for your tiny personal project will work for any of our apps without needing to scale them). Those are separate benefits from monolith app to micro apps (because again, you can do either with either model). You also have some minor benefits that would be easy to work around but are nice to get for free (eg: Github's default history is actually useful in the web UI)
The only tooling you need to manage poly repos is something to do pull requests at scale when something needs to happen everywhere. You can everything else (eg: build management scoped to individual projects) basically for free, you can always clone the entire repo without issues, etc etc etc.