From my experience with Java-style hard module dependencies, this makes it extremely difficult to refactor anything touching external interfaces. You say this

From my experience with Java-style hard module dependencies, this makes it extremely difficult to refactor anything touching external interfaces. You say this forces you to think ahead, but predicting the future is quite difficult. The result is that you limp along with known-broken code because it would take so much effort to make the breaking changes to clean it up. For example, lets say you discover that people are frequently misuing a blocking function because they don't realize that it blocks. Let's say that we have a function `bool doThing()`. We discover that the bool return type is underspecified: there's a number of not-exactly-failure not-exactly-success cases. In a monorepo, it's pretty easy to modify this so that `doThing()` can return a `Result` instead. With multiple repos and artifacts, you either bring up the transitive closure of projects, or you leave it for someone to do later. For a widely used function, this can be prohibitive. That makes people frequently choose the "rename and deprecate" model, which means you get an increasing pile of known-bad functions.