At the beginning, build tools capabilities were relatively simple, i.e. mostly compile and package the compiled sources. But over the years, those capabilities have largely evolved (e.g. complex build processes, dependencies management, documentation generation, testing integration, etc.). And it's probably fair to say that Maven has been, at least in the Java landscape, one of the main actors in that evolution... if not the most important one! Maven is widely used since many years, it's now the de-facto Java build environment. And if you are using another solution (e.g. Graddle), you can't ignore Maven; chances are high that you still have to directly or indirectly use Maven in a way or another (e.g. to integrate a 3rd party framework which uses Maven).
Geertjan then discusses another strength of NetBeans, its Java EE support. He then concludes with "Maven and Java EE are baked into the very essence of what NetBeans IDE is, as its heartbeat, and as its raison d’être". So when you combine NB's deep Maven integration with its outstanding Java EE support, you get a rock-solid (and free!) environment to develop Java EE applications.
Visual representation of a Maven project's depencies in NetBeans
