Because years ago NVIDIA screwed up the thermal solution in their laptop chips so they’d get so hot they’d unsolder themselves inside MacBook Pros, and then gave someone important at Apple the middle finger instead of helping to deal with the issue. Ever since then Apple does not use NVIDIA GPUs.
The fiasco was widely called "Bad Bumps" due to the issue being related to the solder used for the bumps on the underside of their chips.
It was a huge deal affecting major computer vendors like Apple, Dell, HP etc at the time, with failure rates on laptops with these chips being ridiculously high. I've also long wondered if this played a part in whatever reason Apple have for avoiding Nvidia GPUs for so long.
