Because the firewall was built to block things by IP address, and that doesn't help when the content is coming from a distributed network that doesn't depend on IP addresses.
Discussion
Can nostr work on top of this Network?
nostr:npub1acg6thl5psv62405rljzkj8spesceyfz2c32udakc2ak0dmvfeyse9p35c
I don't know what we are talking about. IPFS uses TCP/IP. It is DNS that it doesn't use. The great firewall blocks at the IP layer. Unless you want to use ham radio or ieee80211s mesh networking they can block any traffic on the Internet once they know about it.