There are working Commons in Germany, not sure what you want to say with the emphasis on Mongolia here.
I call attention to Mongolia because graze lands were the most widely thought of example of a 'commons' back in the day and even carried that label specifically. This specific example continues to be observed in that country.
Again, you are failing to be very specific about 'the commons' that you are analyzing. 'In Germany' is still a fail.
Let me quote from the book I was also point at earlier. I found it now.
Hardin's [the one that published the paper "The Tragedy of the Commons" in 1968] argument was a hit because (1) it features an A+B=C simplicity that appears to be inarguably correct; and (2) it is useful in justifying seemingly heartless decisions by entrenched powers. [...] Hardin's articulation of the folly of communal ownership has provided cover repeatedly to those arguing for the privatization of government services and the conquest of native lands.
One other thing Hardin's elegant argument has in common with that of Mathus [does not matter here, thus left out earlier]: it colapses on contact with reality.
As Camdian author Ian Angus explains, "Hardin simply ignored what actually happens in a real commons: self regulation by the communites involved"
[...] any indivdual who tries to game the system is quickly found out and punished.
PhD C. Ryan and MD C. Jethá - Sex at Dawn - 2010
Thus my argument earlier that social punishment of GHash.io and cex.io is the way to go and centralisation/authority or privatization (not even sure how this would work with bitcoin). But lets get to the problem at hand:
Mining bitcoins is the pasture here. Everyone can herd their sheep (start mining) there. There are limited resources (Bitcoins) for everyone to have. If one has to many sheep (over 50% hashpower) in the pasture they risk ruining it (bitcoin) for everyone. A big scale double spending attack would have a big impact on the bitcoin price and thus hurt the attacker. Perfect example of a common that works because if you start gaming the system the angry mob will fuck you up.
You are framing the problem as it relates to Bitcoin incorrectly (IMO). 'bitcoins' are not the resource and don't play a part in things. The bitcoin network is the operative construct. It is supposed (by most people) to be available for common use by anyone who feels so inclined.
I would argue with you and Angus that as soon as control measures come into existence (e.g., getting beat up by an angry mob, or taking defensive measures such as running off your competition's sheep to make more resources available for your own (rather than moving a mile to virgin grass)) then we are no longer talking about pure commons. All you are saying is that 'the commons' are not workable except in unusual circumstances and people adapt. Big deal. Pretty much all life forms face this reality at some point and they all adapt else they would not be here.
Hardin was quite unpopular within many social science communities for his various views and prescriptions. Similar to many of those who've studied other other sensitive topics such as human intelligence. One could achieve instant popularity which was not in alignment with the quality of one's work by 'dis'n' the guy. I think this happened from time to time in his case.
I read Hardin's tragedy work as a kid and several times since. What I took away was mostly the observation that people have a propensity to maximize their personal gain and it impacts corner-cases such as pure commons and exploitation of resources within them. I personally never took from it that 'privatization' was his preferred default way of dealing with the problem. I'm a strong proponent of pubic ownership of bulk resources. I live on a thin strip of private lands surrounded by a state forest, and I am very much in favor of public ownership of resources where it is feasible, though I am opposed to that being the exclusive mode. The state forest (which I am seeing out my window as I type these words) is distinctly not 'commons' and exploitation of it is fairly carefully controlled.