Monoliths aren’t merely monolithic in terms of having a monolithic set of addressable functionality; they are also monolithic in terms of how they access resources, how they take dependencies, how they are built, tested and deployed, how they employ scarce hardware, and how they crash.

Microservices help solve problems that linkers fundamentally struggle with. Things like different parts of code wanting to use different versions of a dependency. Things like different parts of the codebase wanting to use different linking strategies.

Adding in network hops is a cost, true. But monoliths have costs too: resource contention; build and deploy times; version locking

Also, not all monolithic architectures are equal. If you’re talking about a monolithic web app with a big RDBMS behind it, that is likely going to have very different problems than a monolithic job-processing app with a big queue-based backend.