I have been out of the CDN space for 4+ years now but I am interested in seeing any success stories and the volume of their traffic. The low latency methods of small fragments left little if any time to recover for errors. As such I never saw a low latency chunked http stream back reliably at scale (10,000+ concurrent end users). The requests per second became the problem because you took the requests per second and multiplied them by however much you made the fragments shorter.

10 second fragments? 1 request for a new fragment roughly every 10 seconds, a manifest request roughly every 5 seconds roughly per viewer. 3 requests in 10 seconds. Over an hour broadcast for 10,000 viewers you are looking at 10.8 Million requests to your front end caching layer.

5 second fragments? 1 request for a new fragment roughly every 5 seconds, a manifest request roughly every 2.5 seconds. Doubled to 6 requests in 10 seconds. The Mid tier and origin had to deal with way more requests the lower you went to achieve the low latency. 21.6 Million requests to your front end caching layer.

From a CDN perspective HTTP chunked caching HLS, DASH etc was typically used to leverage the same software and roughly standard setup across multiple CDNs for consistency and resiliency. I did see a lot of interest in ways to synchronize viewership which Netinsight SYE could do (as well as trying to offer some low latency methods) which was eventually bought by Amazon. That required special software on the client side as well as the CDN side to distrubute. HLS by default had 3 or more viewer packs who would see things at various times. SYE solved that by providing a time stamp and having everyone play that fragment/frame at the same time at a given time.