I see, the argument is that monorepo facilitates tight-coupling because it's easy to add dependencies. The multi-repo doesn't have the same problem because it's more difficult to have cross module dependencies.

There's a number of solutions to prevent tight-coupling.

1. Language-level visibility modifiers. 2. Build system visibility. Bazel offers fine-grained visibility. I'm not sure about others. 3. Using RPCs as the primary interconnect between services.

My view is that disadvantages of tight-coupling in a mono-repo is a much better problem to have than the disadvantages of having logic spread across different repos.