I am not really sold that going to all of this effort to implement a new communication mechanism is really a better plan than just going with WebSockets, even if WebSockets is not a perfect fit (which they very briefly cover in the article). However, if I am wrong then perhaps someone here could explain to me what I am missing.
SSE are websocks but with a broadcast model. All you need is a websocket open to any of the broadcast sources without providing two-way communication on the socket. Therefore management of a lot of connected clienta becomes very cheap, as you just need them connected to any proxy.that serves your events.