while the 80s crash did lead to nintendo tightening up restrictions to the nintendo NES platform, gabe didn't invent the bsp - that's Henry Fuchs and Bruce Naylor.

everyone had access to bsp tech because it was literally a standard printed in Computer Graphics: Principles and Practice.

Gabe came along later, licensed the tech ID built on top of all that, and that's where Half Life comes from.

The links you assert aren't there.