You said it in a tacky way, but the evidence does suggest that the average intelligence of a population is an important limiting factor in civilizational attainment. It’s necessary, but not sufficient.

Likewise, the likelihood of a startup succeeding is gated by the intelligence of its employees. Successful founders know this and hire accordingly.

I’ve yet to see a sound argument for why it’s ok for a company to discriminate on intelligence, but not for a country to. And of course many countries that are seen as having admirable immigration policies, such as Canada, do exactly that through various proxy measures.