I can understand the motivation here.

One of my hobby open source projects includes multiple services and I don't want to have to start and stop them individually just to test anything. They're designed to run standalone since it's a distributed system but having having to launch and stop each individual process was adding friction that lowered my enjoyment of working on it.

I recently ended up redesigning each service so they can run as a process or within a shared process that just uses LoadLibrary/dlopen (when not statically linked) to be able to quickly bring everything up and down at once, or restart a specific service if the binary changes.

Sure, everything will crash rather than just one service but it's lightweight (no need for complex deployment setups) and made the project far more enjoyable to work on. It's adequate for development work.

Another plus has been a much cleaner architecture after doing the necessary untangling required to get it working.