I do because the quality of av1 on youtube is often significantly better than vp9 and especially h264, even though the filesize is usually lower than both. And the quality of the video at 1080p when only the worse formats are available is noticeably bad.

I can send you some of my DVDs that look like trash now. Of course, that's less of a codec problem and more of a bandwidth/encoder/mastering problem; plenty of DVDs look fine (if a little undetailed) on a larger screen.

I do wish ATSC1 would adopt a newer codec (and maybe they will), most of the broadcasters cram too many subchannels in their 20mbps and a better codec would help for a while. ATSC3 has a better video codec and more efficient physical encoding, but it also DRM and a new proprietary audio codec, so it's not helpful for me.

How is that relevant to anything?