* Strong, mature eco-system
* VM-based so we can easily change OS and/or other dev-ops related params.
* Large hiring pool with lots of experience in it (at least this is the case locally)
* More performant than Python, which would maybe be the next language that hits all three of these points.
Your counter-question also deflects and doesn't answer my original question: what problems can not be solved in Java without frameworks? What are examples of lego problems and duplo problems?
Maybe it's a misreading on my part, but I would interpret a "duplo" language as one I could not even build a framework in, due to a lack of low-level control.