I'm at least as amazed that you can't fathom why people would see benefits in applications being self contained. For all of time, anyone installing anything has appreciated applications that have very few dependencies. At scale, much of the Ops complexity of many organizations comes from matching the production environment with the development environment. That goes away when applications are self contained.

I don't mean to argue that one way is better than another. Of course there are down sides to things being self contained. Just that if you can't understand the benefits of things being self contained, you might not be thinking hard enough.