I don't know. I tend to think that if IBM hadn't had this crazy idea back then, Apple would have had a far bigger share right now. They have been there from the start also but got undermined by the crazy explosion in popularity of the IBM pc. It amazes me even more that Apple has managed to stay in the market nonetheless and are gradually biting off a bigger percentage of it.
I remember seeing a documentary about this very topic a few years back. It is refreshing to see that two sources actually match up 100% for a change.