With a fully distributed model, everyone is essentially running a backbone server. If you don't feel comfortable with such an arrangement, then you'd probably have to opt out. There are plenty of people willing to put up with it, evidenced by the number of companies who have no problem operating the current Internet backbone despite knowing for a fact that their networks are used to distribute child porn and other illegal things. Generally, I think the law is on the side of the distributor, but that's only a legal consolation, not a moral one. I just don't see a way around it. To be fair though, the likelihood of this happening is probably going to be much lower than for a backbone provider, especially if users only serve up content they've consumed themselves (seems like a logical assumption in the distributed system I'm thinking about, but does not have to hold true for all such systems).
I do feel comfortable with being a part of a global backbone server, and you're right, I don't see a way around the moral issue. But I do see a light at the end of the tunnel in the idea of serving what I consume, that is an interesting take on it. But that does also bring up the issue of creating walled gardens (ie niche bubbles) that may not foster the type of Internet I want to see in the future...
For me it's a thorny issue just because of recent articles I've read about the anonymous services really allowing molesters to even set up 'dating' services. As the post above argues about utility outweighing the bad, I want the future great possibilities of an unhindered Web, but I don't want the unheard of new ways people can abuse children. (I've stated before that there are a lot of crimes I don't care about too strongly, but this area gets me, mainly because I have small kids right now)
Perhaps better to take the economical perspective than moral perspective. The coin miner is the backbone of bitcoin, or where all the resource of encryption needed come from, by moral supporters?
Any distributed web attempt must learn from bitcoin and understand the economic ecosystem is required and essential. It beats all pointless endless arguments and find it way to success.
