[gen220]

I think there used to be, before "off-the-shelf" RPC frameworks, service discovery, and the like were mature. There still are, for very small companies.

In 2020, if you have an eng count of >50: you use gRPC, some sort of service discovery solution (consul, envoy, whatever), and you basically never have to think about the costs of network hops. Opentracing is also pretty mature these days, although in my experience it's never been necessary when I can read the source of the services my code depends on.

Network boundaries are really useful for enforcing interface boundaries, because we should trust N>50 programmers to correctly-implement bounded contexts as much as we trust PG&E to maintain the power grid.

That being said, if you have a small, crack team, bounded contexts will take you all the way there and you don't need network boundaries to enforce them.