TCP is connection-oriented, and each connection is a session. IP is decentralized, but the way it's used now in consumer devices makes initiating connections to them difficult and dangerous. Any realistic hope of a successful new distributed web should address this problem, though probably the current solution is "have clients join a private network and route back through it", completely side-stepping firewall concerns. If you ignore the concerns, I guess these protocols aren't that big a stumbling block.