I know that it's infeasible for you to find the ip of a hidden service nor find the clients that connect to said service. However, as far as I understand, the ips of a hidden service's introduction points are public knowledge. Can't the feds, who want to shut down illegal services like The Silkroad, just target its introduction points to prevent people from connecting to it? They can just do that constantly every time The Silkroad change their introduction points and they will never be able to service new clients that haven't rendezvous with them yet.
The introductions of hidden services are actually just random Tor relays chosen anonymously. DDOSing them won't work because the hidden service can choose other Tor relays to act as introduction points and you would only be removing relays from the Tor network.
The only actual way to shutdown illegal hidden services is to shutdown the acutal server of the website. Otherwise, the Feds would have easily shutdown every illegal hidden service.
This is one of the massive control vectors, i.e. if you're controlling/operating like 50%+ of Tor network nodes - then yes, it can be an issue. Otherwise - no, it's properly distributed through the network. And this question, actually, shows us the importance of running your own node for everybody: a Raspberry Pi or another SBC will not consume much power even being online a month non-stop, but will speed up your privacy and the network itself.