I'm old enough to remember.
They worked with studios to optimize games for their hardware. I don’t think they went around sabotaging other companies hardware. They did what was good for them.
Why did competition not do the same?
AMD could’ve done the same.
While ATI and Nvidia never tried to implement a Glide emulation layer, several hobbyists did and 3dfx shut them down with legal threats
Were there any legal barriers to ATI/AMD or Intel implementing CUDA or PhysX on their systems?
No gamer had a problem with nvidia.
Many bought their mobos and video cards.
Mac was pretty hated, Steam was very hated, we didn’t bow to any software company.
Nvidia actually made hardware.
Your propaganda is so awful because it’s always obvious you have no experience