That's a good argument, but I didn't see the "we want the best people we can get with what we want to pay regardless of where they are." Which is what some companies do, they hire from all over the world and pay them in the same range.

Why should companies hire only from the US if there are as good or better people elsewhere?

You're looking at it from the cost reduction perspective, but work shouldn't be something you save money on, but invest it the best you can to get the best product.

In summary, looks like the CEO and CTO of your sample companies don't know how to collaborate remotely. Which is natural because it's not intuitive. And if you don't know and don't want to learn, or happen to be at a niche not amenable to remote collaboration, sure, stay at an office.