I don't think some people actually know, what they claim to know.
The most logical and likely situation is that early access was provided to vendors to get them testing it to make sure the game ran acceptably, optimise if possible etc. AMD came back to them and said, in certain situations (RT + Dynamic res + 7900(?) series cards), the game crashes, and we believe this can be solved with drivers. Nixxes goes cool, well to make sure that many thousands of people don't start playing day 1, experience those crashes and complain (that's way worse for us all), we'll make it so if the game detects AMD RT capable hardware, we'll make RT greyed out, they'll still be able to play the game then without crashes.
AMD themselves meanwhile still have access to the full/earlier game to test their driver efforts against, then when AMD says they fixed the crashes, they release the driver and tell Nixxes, who roll back the RT greyed out portion of their code in a subsequent patch.
We've seen nothing to indicate this is an actual game code problem, all of the issues seem to be specific to AMD RT capable cards, and 7900 series at that iirc. And nothing in what Nixxes themselves have said indicates the problem was theirs to solve, just to aide vendor with by making sure significant portions of them wouldn't experience a known error that was easy enough to work around.
If it was just a game coding problem, and nixxes had to put in significant work beyond greying out and subsequently making available certain options based on hardware detection, then why did it need a driver, that specifically says it resolves the crashes.
I won't sit here and say I know this to be the case, but it certainly seems more likely than an actual game code issue, or lol, an nvidia sponsorship issue.