Who's going to pay to create all the nodes. You need a lot of them in normal times when it is just enthusiasts sending test messages and if large numbers of people start sending real messages you will need more.
paying to create the nodes isn't the hard part. The hard part is the protocol isn't designed for this and is easily overwhelmed. In case of adversarial attack, it's trivially going down because the protocol is easily attacked, as we see at any popular gathering like Defcon.
