The monorepo is where you end up when you have failed to enforce encapsulation and your "modules" do not have stable APIs (or are actually modular). Then, with

The monorepo is where you end up when you have failed to enforce encapsulation and your "modules" do not have stable APIs (or are actually modular). Then, with sub-modules each change will often involve multiple commits to different modules, plus commits to update references, so O(N) commit multiplication.