Byrne’s argument isn’t that YC is a better HBS, it’s that it’s a better Harvard. You need a Bachelor’s and normally at least two years work experience to get into HBS, but not Harvard or YC. They both work primarily on selection, not treatment although there is a real treatment effect. And YC both pays you money to go there and has an explicit right to some of the products of your future success whereas Harvard doesn’t have any rights to anything but tuition fees though they get plenty of donations from alumni.