It's not just keeping things separate, though. It's getting the dependencies in the right direction too. I'd argue that's actually the most important part. A

It's not just keeping things separate, though. It's getting the dependencies in the right direction too. I'd argue that's actually the most important part. A lot of people would look at the decoupling in a hexagonal app (or something along the Clean Architecture lines - they're very similar) and say that you don't need that much decoupling, but the patterns are very powerful; deciding to opt into that power early is a good choice to make more times than you'd think.