[Teever]

Because you need a license to do so and Intel and AMD are loathe to give a license to would-be competitors.

I believe that the person you're replying to is referring to an attempt to produce x86 compatible processors that Nvidia undertook when they bought the license that Via owned.

IIRC that didn't go so well for Nvidia because the license didn't include new parts of the instruction set like the 64 bit instructions that AMD made in the mid 2000s and AMD wouldn't license them.

[DeathArrow]

I do believe they've tried to circumvent the IP by implementing a translation layer like in Transmeta Crusoe, but Intel still threatened them with lawsuits.

[papercrane]

Nvidia can't do a translation layer. Back around 2010 Intel and Nvidia were suing each other, the settlement agreement specifically said Nvidia wouldn't produce anything like that