That's purely hypothetical. How could any prove or disprove the assertion?
The general point, though, is that consumer awareness is essential for sales. People won't buy things that they don't know about. As an indie developer myself, I'm painfully aware of this. It doesn't matter how great one's product is if nobody knows about it. Advertising is very expensive, so it requires vast capital outlays in order to get your products into the minds of consumers and onto the shelves of stores. The big established brands have a massive advantage, making it difficult for competitors to break into the market. Apple itself leveraged its existing brand, with Mac and iPod, in order to promote iPhone. And Apple's primary competitor is Google, who also was already an established brand via search and Chrome.
Remember that back in the day, Microsoft almost destroyed the entire desktop OS market. They almost killed Apple too. Only the Department of Justice put some kind of break on it, and Microsoft let Apple live in order to provide antitrust cover. If MS had for example simply withdrawn its apps from Mac—Office, Internet Explorer (remember that Internet Explorer was originally the default web browser on Mac OS X before Safari!)—Apple likely would have died.
The hardest part about switching from Facebook isn't installing some other app or anything like that, it's getting everyone else you know to switch from Facebook.
The hardest part about switching from Windows isn't installing Linux, it's getting e.g. game developers to target Linux before it has significant consumer market share.
That isn't to say that doing these thing is impossible, but it certainly isn't trivial, so anyone wondering why it hasn't happened already can't seriously think the only explanation is that nobody cares. It's like saying nobody cares about high healthcare costs -- of course they care, the question is what do we have to do to fix it?
Now, how many of you guys have this? Or anything like this? I bet 95% of the HN crowd happily uses iOS/Android daily.
Anyway, desktop computers aren't really the main problem here. For example, Apple Macs offer vastly more personal freedom than Apple iPhones. If iPhones behaved like Macs in that respect, then we might not be having this debate. To the extent that Macs have been increasingly locked down over the past 15 years, it's mostly just copying the iPhone, porting the "features" over from one platform to the other.
That's quite an assumption.
Really? Please name them. Over the past 10 or 15 years, I've never seen anything other than the iPhone/Android or Mac/Windows duopoly for sale in any retail store. I've never seen any advertising for other than those duopolies. The HN crowd may be aware of obscure options, but for the vast majority of consumers, they don't exist. And since we as developers make money catering to the vast majority of consumers, we're kind of stuck with the duopoly too, at least as far as our work is concerned.