Why is still gnome and not kde the default Ubuntu Ui?

Shoutout to the fortresss forever mod that ported the original team fortress to the source engine https://store.steampowered.com/app/253530/Fortress_Forever/

I have never heard of anything like it being done before. Usually only small changes are possible in the Genome of complex organisms. Not a whole new organelle.

Their incompetence opens room for other platforms