Earlier quoted context omitted.
There are some interesting theories being tossed around. I'd like to add one more. The common thread across all darknet websites is the fact that they generally run from datacenters. Most people don't host websites from their residence. Further, most people don't colocate servers anymore. I would be surprised if any of the 414 websites operated on boxes that had been colocated. However I won't rule out that colocatin…
>You can't rent a server from a datacenter using bitcoin Why not? A google search for this reveals several companies who offer this.
There's the chance that datacenters will be more inclined to image your server for authorities if you've set up a server using bitcoin and are hosting large amounts of Tor traffic, but at this point we must assume authorities will image your server anyway, so there's no reason not to go this route if it's as good as you say.
You may need anonymous money for other things, but server rental was the primary case I had in mind.