They’re paying to use Dolby’s encoding schemes. It’s not the idea of “stereo audio” that’s patent encumbered, it’s some of the encoding schemes that can output stereo audio (much less so these days, patents are expiring and all of MP3’s have). Same with surround audio and spatial audio and HDR: Dolby has an encoding scheme that works well and gets the desired result, is high quality, usually higher quality than the alternatives, and they market it well.
I’ll welcome anyone that wants to enter the space that thinks they can do better, but Dolby is good at what they do, and Google often has massive commitment issues for new projects (although notably, not usually when it comes to codecs). I suspect what will happen is YouTube will develop their own HDR and audio codecs, and it’ll just be used on YouTube and almost nowhere else. That’ll be enough to drive client support, but it’ll be one more HDR format in addition to HDR10+ and Dolby Vision, and it’ll be one more set of audio codecs in addition to like the half dozen to a dozen they already decode, and ultimately this will be to increase the quality of YouTube while minimizing their licensing costs. That’s fine.
I’ll welcome anyone that wants to enter the space that thinks they can do better, but Dolby is good at what they do, and Google often has massive commitment issues for new projects (although notably, not usually when it comes to codecs). I suspect what will happen is YouTube will develop their own HDR and audio codecs, and it’ll just be used on YouTube and almost nowhere else. That’ll be enough to drive client support, but it’ll be one more HDR format in addition to HDR10+ and Dolby Vision, and it’ll be one more set of audio codecs in addition to like the half dozen to a dozen they already decode, and ultimately this will be to increase the quality of YouTube while minimizing their licensing costs. That’s fine.