I think people shouldn't underestimate the way people counter react to rules they do not like or agree with on some level.
Judging from observing my peers, extrisinc worked better in long term. With few exceptions, those whose parents did not restricted gaming just continued to play really a lot. Those whose parents did were more likely to discover something else to do.
But yeah, it definitely requires certain circumstances, and it's not realistic for everyone.
"Externally imposed restrictions" is what parents and society do. Then, internalising and understanding these restrictions is part of the education process.
Children are told not to spend too much time gaming by their parents (hopefully) and said parents also impose restrictions when this is not so (hopefully), for instance.