I don't believe in this assumption -- "There are certainly some combination of country/startup where the founders would be better off in Silicon Valley - when we are talking about founders who need visas (they can't get EB5 green card which is given based on investment or business visas which are pretty much given to anyone who has valid established business or who are not already in US as a student/employee..in that case founders do get H1B easily transferred for their own company provided they can show company of substance..if they pursued advanced degree here then they don't get in H1B cap)..so limits to be the people without much of resources of their own - who don't understand market here (at least not on first hand basis) and don't have connections..how will they succeed.. why misguide some of them and also fool ourselves that such a thing is useful..especially, given there is much better chance if they stay where they are then they will be able to pull off something successful targeted at the market they already understand
and that too putting up number of 2500 such startups every year ..good idea to write 2 examples to validate it first..tell me some story..
so my point..people should start company where they understand the market and if US wants to benefit from international resources then investors should go outside US because only that will work..because that is right for startups/founders/investors..