Internet is super easy to kill, just shut down all the ISPs and there is no internet any more. The same goes with blockchain technology, they just need to block the access to those IPs running them. Of course they can´t shut all nodes but they don´t even need to.
Sadly internet is very complex and therefore centralized (in order to maintain it) while we could implement an internet that sort of works like the blockchain (p2p) not much effort or research went towards it so far (hope that will change).