I think I could not disagree more. Coupling and cohesion are problems you will have, regardless of the repo approach you take. But a mono-repo gives you a host of incredibly beneficial advantages, especially for larger organisations.

Any downstream library team can instantly tell if their change has broken any upstream users because a good CI system will just automatically run all tests of all relevant projects. That way a library developer can either iterate until all projects depending on it are green, or the library developer can even proactively change all dependant projects and roll all fixes out in a single atomic commit.

This has proven incredibly beneficial to our development speed and the number of avoidable code conflicts that crop up.