There were maybe 2-3 years during the last decade where H1b quotas were much smaller than demand, so what - it just took some folks a bit longer. I don't know anyone who wanted to relocate here but couldn't due to visa issues. Lack of a healthcare system is what actually scares people away, yes even young ones.
I'm all for erasing borders, promoting "citizens of the world" thing, whatever. But there are so many real issues we need to solve right now, that visas for founders seems like an aid for lazy.
We all know a famous saying/advice for first-time CEOs/entrepreneurs: "if you can't get an introduction, you probably won't be able to run a company", similarly it can be said "If you can't get into the US you probably won't be able to start a business".