Fruits of evolution. Blocking information is a battlefield where the overseer can either win very easily or cannot be able to win---the only fundamental way to block anything is to block everything.

Imagine if your ISP blocks the front page of The Post yet you are still allowed to talk to me. Well, I can simply read the information to you over the phone under a plausibly deniable "eg even number of words in a sentence =1" algorithm.

Years and years of cat-and-mouse between people wanting to jump the Great Firewall and people maintaining the Great Firewall.