The DOJ presser said the site was "larger" than Netflix, Hulu and Amazon combined in terms of available content - some media reports have misreported it as larger by subscriber count
"Tragedy of the commons" is when a bunch of private interests use a publicly-owned resource in a greedy way and end up ruining it for everyone. I don't think this quite applies here, but I don't know of any other term to call it because I can't think of any non-internet analogies.