Mostly agree with this, the issue was that Spring Framework 3 introduced a new way of doing configuration with the @Configuration annotation. Up until then it w

Mostly agree with this, the issue was that Spring Framework 3 introduced a new way of doing configuration with the @Configuration annotation. Up until then it was all xml driven (some minor packages like spring-integration still required it) bean soup. The advent of the annotation driven configuration paved way for spring-boot to provide sane defaults to the framework (previously reserved for certified spring framework engineers like myself to define in xml that we copied time and time again). You nailed it though with Spring being configuration over convention and Spring Boot being the opposite. At the time, there was a competing web framework that was really simple to build with called Rails that made the mindset shift to ease-of-use from a dev standpoint away from ease-of-use from an ops standpoint.