[hackerfromthefu]

Look this is a great answer, and I love Martin Fowler. That's one rational explanation. It may however be a rationalised explanation that misses out on the difference that makes a difference to understanding what's really going on.

So here's another perspective, that of a software anthropologist .. .

Common patterns of networked systems were developed over decades, and as it developed over decades it built various advanced features on top of the core network call/response features - service busses - routing - useful abstractions like decoupling services from host processes - propogating security contexts through the chains of service calls that can develop when these systems evolve - strong typing, which enabled layers of tooling to replace manually doing jobs with these systems and various advanced features.

That was called SOA, because it looks at software architecture as a set of services.

Then along came a bunch of programmers that weren't very studious, started from scratch just doing basic message passing without all the advanced features that had been built up by the decades of previous hard won lessons. That was called microservices. Note the removal of the 'architecture' from microservices!

slightly /s