Each component is testable, upgradable, and swappable in isolation. There are no technical issues with doing so. What is missing is interest in implementing and

Each component is testable, upgradable, and swappable in isolation. There are no technical issues with doing so. What is missing is interest in implementing and testing a full-featured alternative to some of the components. As soon as that alternative exists, it's usable. You wouldn't say that a company lacks a microservice architecture simply because they don't have unused reimplementations of each microservice lying around, would you?