From my memory: In the 90, if you had anything to do with computer graphics[1] you knew about binary space partitioning trees.

Off the top of my head I remember two different articles from local German computer magazines (that are still in my basement) discussing and implementing them.

But so were many, many other ideas and approaches.

Not taking away from Carmack's genius, in my opinion it was not in inventing a horse and neither in finding one, but in betting on the right one.

[1] If you were a programmer in the 90s - any kind of programmer - you most certainly had.