> MPEG-DASH live streaming
IMO that was more dictated by server-side complexity. A multimedia streaming server, especially for live video, that is optimized end-to-end for robustness and efficiency can be a very complex beast. Streaming transcoding, metadata injection, buffering, etc are difficult on their own. Doing them together in a unified fashioned is especially difficult. Solutions like GStreamer that abstract this away and make it conceptually simple are also extremely inefficient at scale. (Take it from someone who wrote an entire end-to-end solution that could do M:N codec, format, and transport transcoding, per-user streaming ad injection, and a bunch of other stuff. I could do 5k+ live audio streams, each with unique ad injection/splicing, with most of the pipeline occurring on a single E3 Xeon core--the socket writes to 5,000 clients from a single thread and the resulting ethernet interrupts that caused that CPU to max out. Reusing solutions like GStreamer or FFmpeg directly in your pipeline you'd be extremely lucky to get 1/10 of that, and more likely 1/100 at best.)
MPEG-DASH permits the incoming media processor to simply dump a bunch of files to disk. The client facing service can then serve those up however it wishes--it can be completely dumb or incredibly smart, but importantly both halves can evolve on their own. You could do codec and rate transcoding as a third, middle component. And you could break these components down even further, as "everything is a file" is the most basic IPC interface we have. This makes iterative development much easier.
IME, MPEG-DASH is pretty much what you'd get if you began with stodgy old (relatively) commercial broadcast equipment using nasty broadcast framing standards and organically built a streaming pipeline from scratch, without ever having the benefit/burden of knowing how to do performant streaming server development, or even how existing solutions worked. The multiple files non-sense was never necessary for client compatibility or network filter bypassing. Apple had solved that with RTSP-over-HTTP tunneling years prior, as did Flash with its clunkier RTMP solutions later.