It’s no all black and white.
Mobil1 does not use 100% group IV PAO in all their oils.
Most oils are a blend of the various groups. Even some “dino” oils have some group IV blended in.
It’s all about meeting the spec. At Bobistheoilguy they mull these things over endlessly.
Me, I use any major brand “dino” I find on sale that meets my car’s specs and change at 5000 miles or 1 year.