but I'm not sure what good that does when you can bypass it in a second with a proxy.
Plausible deniability. ISPs are more than aware that users are using proxies, VPNs and Tor to bypass all the restrictions they put in place and view blocked material or torrent illegal content. But that can't be easily proven from IP logs, so they can't be taken to court over it. All they need to do is the bare minimum which the courts mandate (such as block piratebay.com whilst ignoring the .net, .org, .it, .biz, etc., sites), whilst also maintain the maximum amount of freedom so they keep customers.
It's crazy to think that governments still try to censor certain things.
It's only getting more common. All Western governments are increasingly censoring more and more material, and spying more and more on their citizens via Google, Facebook, etc. The latest story I say was that the US government are demanding Facebook install a backdoor to WhatsApp to allow them to access everybody's messages unencrypted. Governments want control.