To be totally honest, my theory is that the closed shop is real as at the very top of near all sports, the sport part is forgotten and it becomes business first, second and thirdly which means that as with all top end business it is dog eat dog and who cares about the people burnt or hurt on the way.
If you look at the true top end of all sports, the vast majority have a somewhat closed shop approach with eligibility rules designed to make access difficult, target markets dictating the competitors, sports administrators with self serving interest, media with agendas etc. But you then drop a rung or two and whilst still a business the sports element is again present where you see a friendlier atmosphere, more approachable athletes and so forth.
Money drives all unfortunately and for mine, Spies is a great example of talent that has been wasted/lost to the sport (fans) in the pursuit of the almighty dollar.
Now, I do not believe that Spies would have won a number of world titles in MGP as the field is just to strong and he is not a Marquez, but he was (IMO) at a level easily comparable to a number of factory riders