This is a poor take away. Even in a monolith, you still want to separate your concerns, yes? Your code should be almost as abstracted in a monolith as they are in micro services. In microservices the code is just deployed across multiple instances.

RPCs and local method calls both need to be fault tolerant and race condition free. As you break up datastores, transactions become more complex but certainly you had a specific reason to do that so the complexity isn't a choice.

Sure the communication layer is added complexity but that too is should be abstracted into boilerplate such that you shouldn't have to think about it. Overall the added complexity requires more work but it shouldn't really make your business logic problems more complicated.