She showed that the commons wasn't the common element in systems that weren't sustainable. If the "tragedy" is that every commonly-held asset is doomed to destruction, and you have common, predictable examples of ones that don't, the thesis is debunked.

>The problem is that those conditions are much harder to maintain in a highly mobile, anonymous modern society.

This also isn't true. You don't need identities when the heuristic is behavior, and action can be taken by either the public or by agents empowered by the public.