The basic concept, as I understand it, is that the more isolated each thing is, the easier the maintenance, changes, etc will be. Let's say Fulcrum needs way more RAM; I could just move that container to a different host machine without reconfiguring anything else.

Or let's say I'm trying to install some tool or app, I follow instructions to install all these dependencies, and then find out that info was outdated or that those dependencies cause other headaches. Oops, too late, already inserted those dependencies into way too many places to try to undo. Even worse if I did that in the Linux OS that runs my main bitcoin node.

I've restarted a Docker + mempool install twice now by blowing it away and starting clean. It just frees you to really iterate through try, fail, retry cycles.