I have seen monoliths successfully transition parts of their functionality into small services. I have not seen a microservice-first approach work very well. Wh

I have seen monoliths successfully transition parts of their functionality into small services. I have not seen a microservice-first approach work very well. When you're building something new, your intuitions about which parts are going to be tightly coupled and which parts are going to be relatively independent are just guesswork. Once you've iterated on a monolith enough to see which parts are relatively independent and would actually benefit from decoupling, then you can move them into separate services. One example that comes to mind: I wrote a recommendation service that also handled user feedback events. This was the easiest way to start. After about a year I saw that we were iterating faster on the event processing than on the actual rec delivery. We were also deploying this monolith across more machines mostly to scale up event handling capacity. So we broke the high volume event handling out into a separate service that was smaller and optimized exclusively for event processing.