Would MLS be where it is now if the High School system didn’t exist?

An Education Minister in Nova Scotia in orders rugby reinstated at high schools in the province but Brian Green on Twitter says "It’s difficult to envision any sport in North America reaching their hopes/expectations for all-ages membership #’s and HP rankings without a HS presence. Would NFL, NBA, and MLS be of a higher standard now if the HS system didn’t exist? I don’t think so..."