In the real world, not all problems decompose nicely. In fact, I think it may be the case that the problems we actually get paid to solve with code are often of this type.

Problems like?

Depends on what kinds of problems you're solving...

I'd put it in line with monolith vs microservices... You're shifting complexity somewhere, if it's on orchestration or the codebase. In the end, the piper gets paid.

Also, not all problems can be broken down cleanly into smaller parts.