In practice they want people of high ability who will contribute positively to the US, not necessarily geniuses. My friend who was supporting actress in some Netflix thing got in on that basis.
O-1 isn't a genius visa, it is for [1] Individuals with Extraordinary Ability or Achievement, the government website specifically calls out categories that are not research or engineering.
Why not both? I can see the argument for not having millions of unskilled immigrants crossing from Mexico but both Dwarkesh and the researcher/engineer would benefit the US. I don't think it's that hard to get O1 as a researcher/engineer - you basically have to get to the level where you present at conferences and are seen as an expert in whatever.