You can make shallow clones, and auto push to a single repo, it's common to for example auto push to Github from an internal repo. It sure has it's issues, but

You can make shallow clones, and auto push to a single repo, it's common to for example auto push to Github from an internal repo. It sure has it's issues, but problems are solved with solutions, simply bury your head in the sand, eg. using single repos where a monorepo is the best solution - is not a solution.