The technology hasn’t advanced in this regard. When a class A amp can double its power into half the load impedance, its simply because its built to be able to do that. The technology to do that has been around for decades
+1
This makes absolute sense. Either it’s a legitimate true class A designed and built circuit or it isn’t. Amplifiers that claim generous class A power and are barely warm to the touch are suspect to me. Perhaps some degree of class A biasing but not genuine full “A” circuit.
Charles