Most comments about this assumes a poorly designed monolith and a well designed set of microservices. A microservices architecture can be a rats nest too.

I guess what it means is that even if you can build a well modularized system, it will only stay well modularized if you use a network call to enforce it. Well, at least for most companies.

Conceptually, there's nothing keeping you from designing your codebase to work as both microservices or direct calls. I've certainly done it before - each service defined a Java interface, and codegen could hook that up as either a direct call or to route over some kind of layer.