Here's my stance...
Apple is a company that upholds quality and makes everything that they do above and beyond the rest of the industry. This earns them the right to be proprietary.
Digidesign, on the other hand, "introduces" features into its buggy Pro Tools bundleware about 1-2 years behind the competition, and their hardware is notoriously overpriced, while bringing no advantages over most other digital audio hardware on the market.
The reason why they are the "standard" is BECAUSE their products cost more - which increases the perceived value to the consumers, especially large studios that are used to paying tons of money for their setups. I'm not saying you can't make great recordings with Pro Tools, obviously it's done all the time. Ultimately it's all in the hands and ears of the engineer.
My fear is that DigiDesign will edge out and marginalize the competition to such an extent that the progress of the software will be slowed to even more of a crawl.
All this being said, lately I spend far more time in Pro Tools than Digital Performer. My producer is a die-hard Pro Tools fanatic, and he does great work in it, so it is a lot easier for me if I stay on the same platform. I can't be alone in feeling the way I do, though... if Pro Tools truly was the best, I wouldn't be bitching about their "monopoly."