@aral I think you misunderstand.
I'm not a GNOME Shell developer, it was just my educated guess of the probable practical performance+legal tradeoff that occurred a decade ago.
Nobody closed nor opposed @YaLTeR's issue 3371 that you linked there, nor other issues AFAIK. It's just impossible without HW encoding for VP9/AV1, IMHO.
VP8 is the only usable "in software" Free codec out there. I know because (from experience) you typically can't encode VP9 realtime "in software".