@sun @icedquinn @meeper @maija I don't think it failed technically.
Just takes an awful long time to rebuild a graphic display protocol from the ground up plus adapting the existing software for it to the point where everyone already using X11 can switch without hitting a regression. And I do mean a regression, not spacebar-heating, which let's be honest tearing for games is.

And of course socially you end up with usual open-source nerds cat herding.
Like OStatus→ActivityPub worked remarkably well and I think that's just because there were basically just ~3 implementations involved with few developers each and a pretty small and straightforward protocol in comparison, and most admins/users had nothing to do.