There's probably nothing to stop them, but it's way more hilarious. Anonymous internet people start using the networks for various flavors of illegal file storage, and various innocent network operators just trying to sell shovels in a gold rush or run a simple pyramid scam start getting sued by the RIAA or prosecuted by the FBI, while the original uploaders (or even the smart contracts to maintain and index the uploads) are dust in the wind.

I don't think I'd call random innocent people getting served with lawsuits "hilarious".

It's hilarious because people have been jumping into running services without necessarily considering the legal liabilities they've been signing up for.

It's like if someone started a point-to-point delivery business where they take anonymous, secure packages between different places, no questions asked, and then are surprised when the police show up and say they're pretty sure that a good portion of the packages they've been carrying are drugs and pipe bombs, and ask them to roll on their clients, or at least stop delivering packages. And then the delivery man tries to make a philosophical argument that they aren't morally or legally responsible for the contents of their packages, and in any case it really shouldn't be illegal to distribute drugs or pipe bombs.