SS came out in 2008, HLS in 2009.

Separate manifests and non aligned segments have a real impact on the ability of the client to switch qualities in responsabilità to bandwith change, and this to avoid stalling.

BTW, when I say "HLS is pretty backwards" I mean designed unergonomically and without clear requirements in mind, not a step back from what existed before. I would guess this is because the original specification was something like "whatever Major League Baseball can easily stream from their existing setup" (see the various Pantos drafts that ultimately became RFC8216)