I mean, has there any empirical evidence disproven any of those base assumptions?

In econ the easiest part is to create a model, the hardest part is seeing it crash against reality. But the basis of monopolies seems to be pretty thoroughly tested. The biggest issues you have now are Chesterton Fence's. Were its hard to know what laws and regulations are therefore safety, parity and economic performance and ones are only creating friction with no benefit due to years of laws being put on top of other laws