The scalability of DASH/HLS comes from the fact that the video segments are just static files sitting on a http server so they can be cached and distributed with the many techniques for serving static files over http.

If you don't need the scalability of DASH/HLS you can use the WebRTC apis for low latency streaming, usually <1s. WebRTC can be used for client-server applications just as easily as peer-to-peer using a gateway like Janus[1].

[1] https://janus.conf.meetecho.com/

It can be done

http://www.gpac-licensing.com/2014/07/09/lowering-dash-live-...

HD RTMP to the client is extremely difficult to scale without an enormous investment in infrastructure. AFAIK BAM/MLB.TV are the only ones doing it.

Abusing WebRTC can be a viable option in latency-critical applications, but it brings a bunch of other concerns with it (browser support, no way to leverage a CDN, etc).