If you'd taken any econ you'd know that differentiating factors exist which essentially create a 'new' market. Whole Foods doesn't compete in the same market as Wal-Mart. Louis Vuitton doesn't compete with (insert nameless brand... Not sure, my wife likes high-end things).
Anyhow, the comment was meant tongue in cheek anyhow, don't know why you're so upset. Your retort was bad anyway.
There's a very large segment of Apple's customer-base that are in a different market, even if there appear to be competing products. Some developers have no interest in anything other than a MBP. Ditto for a large number of iPhone and iPad users. There will always be those who switch, in the same way that someone may shop at Whole Foods and decide that it's not worth the price.
This is actually pretty consistent with Apple's entire history: they've resisted commoditization, even during times when it really hurt their market share.
Anyhow, the comment was meant tongue in cheek anyhow, don't know why you're so upset. Your retort was bad anyway.