I think it's a pretty reasonable split of responsibilities, and not uncommon.

Eg: JDK + maven + junit + tomcat

Making these components pluggable is arguably how we get innovation (eg: yarn/pnpm, jest/vitest, etc)

Is this the old monolith vs micro-services argument?

I guess this boils down to 'how granular and function specific are your building blocks?' and where you draw the lines programmatically: library interfaces in a single program/executable, API/ABI between two or more programs/executables, HTTP API/other transport protocol across network boundaries between two or more programs/executables, and so on.

I'm not sure I'm slicing this along the correct abstractions, though.