I remember hearing about China usurping 15% of western internet traffic for 18 minutes. This was accomplished by having nodes report as being the next closest hop in the network path to the packet destination. In a decentralized darknet project, I imagine such an issue being much more widespread. In fact, I would imagine a darknet project would actually play in to the hands of the government. It would be perfectly plausible to infest the darknet with millions of your own nodes reporting as the next best hops thus inserting themselves in the middle of all darknet traffic able to analyze data as it flows through the system. Obviously, a darknet would utilize encryption for traffic but all bets are off when you potentially have a constant man in the middle and no centralized authority on trusts. What's worse, and more to the point of playing into the hands of the government is that a darknet would give them (the government) a concentrated focus area. If I were to categorize the percentage of traffic that was "interesting" for regular internet traffic vs. the percentage of "interesting" traffic of all darknet traffic then I would imagine the darknet having a much higher ratio of noteworthy to junk traffic. If I had a limited amount of resources to invest in analyzing and decoding secure traffic I would obviously point my tools at the most richly dense data source.