I like the approach of building a monolith (with smaller libraries), and then split it once you need to. The argument is that you're likely to choose the wrong services to seperate until after you've built a bunch of the system.
I never worked with a client that built libraries (eg. Jars or dlls, etc). The reason was because it was hard and took effort. So we ended up with monolith applications.
Fast forward to today we have essentially jars and Dlls with the added overhead of an entire system and deployment to maintain.
