The HLS integration we offered definitely had a premium attached to it as well as an additional cost to the CDN that required the integration to live on. So it’s not cheap.
It is weird that Google, with it’s infinite pockets, hasn’t pushed a stream stitched solution all these years until recently.
You are correct, which goes into the cost category of doing a stream stitched integration. Also, when I left said ad server in 2016, I think I recall HLS streaming primarily supported by Apple devices. Devices like Roku’s (don’t quote me on that) didn’t support it at the time so a lot of companies looked at where the majority of their streaming was occurring and decided it wasn’t worth the hit.