That is far easier said than done. If the streaming is point to multi-point then the crypto can get tricky, if you allow people to join and leave the group at

That is far easier said than done. If the streaming is point to multi-point then the crypto can get tricky, if you allow people to join and leave the group at random it gets tricky, and keeping it all working without providing a list of the participants to each peer is tricky. With BitTorrent Bram started out with a system that had strong crypto and privacy (Mojo Nation) and stripped most of it out because it increased the complexity for little benefit. Strong crypto and privacy have costs, both in end-user resources and bandwidth implications. Getting it all correct is hard and if you screw up a little it is usually worse than starting from the position that privacy and a secure channel is something that the user has to bring to the table if they really want it.