it's not really "micro" but more so "discreet" as in special purpose, one off. to ensure consistent performance, as opposed to shared performance.
yes, networking is the bottleneck between the processes, while one machine is the bottleneck to end users
> one machine is the bottleneck to end users
You can run your monolith on multiple machines and round-robin end-user requests between them. Your state is in the DB anyway.