I think it does. From the very beginning they wanted to sell computers to people by making them think they work like home appliances. If people knew computers are actually universal machines, then they wouldn't be as willing to pay more for the same components with a different brand printed on the machine's case, or a different software running in them.

Besides, that gives them a single competitor to fight against.

Is it really easier to face one big nearly monopolist opponent instead of two who're fighting against eachother? Also one important obstacle for the adoption of Apple products was the common notion that there's no plausible alternatives to buying a PC. That's why they invested heavily in sending the message of pluralism - "think differently" etc.