A duopoly is a choice. Not a lot of choice granted, but still a choice. There are also other platforms (like Samsung etc) but you won't like them for other reasons.
I don't think you understand the point. You're taking about poor decisions that those companies made several years after Apple and Google entered the market, but ignoring the years long head start that they had and squandered. Why weren't Symbian, BlackBerry OS PalmOS, or Windows Mobile good enough in 2007 to not get obliterated by two brand new platforms?
At some point we have to admit that one of the main reasons for the duopoly is that the rest of the competition wasn't that good.
You have the choice of starting a competing company. You can convince investors that there is in fact a market who are unsatisfied with the current options which can sustain your new company. Of course, if everyone is satisfied with the current options it will be difficult to get investment, but then there is no problem either.
The whole world will be against them. Nobody wants to develop apps for dozens of different competing platforms. In fact, for the longest time, I thought this was the reason Android/ open handet alliance exists but nobody talks about OHA anymore.
That's an important point. Microsoft wasn't lacking the resources to develop a phone OS and Windows Phone didn't fail because "it sucked".
Instead it's a demonstration of the power of two-sided markets. When Apple came out with the Apple ][, Silicon Valley had a competitive advantage in electronics because of networks across firms. Need parts? Need specialty talent? You got it.
Now the "competitive" edge of Silicon Valley is that it is the home of great monopolists such as Facebook, Apple and Google. That is, it crushed the competition and prevents it from emerging.
There's also the reality that (1) brands feel the need to express their brands through apps, (2) they are already annoyed enough that app development cost is at least doubled because you have to support iOS and Android, (3) many would express the belief that being forced to develop apps for a third (fourth, fifth, ...) mobile OS would be "extortion" or the equivalent. My understanding was that Windows Phone went EOL because carriers in the US were refusing to activate them because they too think it is bad enough to have to be able to deal with two OS.
If Android didn't exist, however, you'd probably being paying less than a 30% rake to the app store because the App Store would have been seen as a monopoly and the court would have done something about it. As it is the zombie OS Android doesn't really make money for Google or anybody else (Samsung is just proud it makes phones) and wastes money for app developers but it does make money for Apple. From that perspective a third mobile OS is like a fifth wheel.
There is such a thing as "pernicious competition" where fake competitors prevent the entrance of a real competitor, for years cable TV was a great example because you'd see several cable operators, several satellite operators, and later several IP based operators that all offered the same crummy channels with the same crummy UI at the same high price. Not only did the cable operators not serve the same customers but the structure of the industry caused them to "collude" to offer customers the same thing.
Android is like that. It adds $10-15 billion profit a year to the Apple App store just by keeping the court away.
I don't like iOS and I don't like Android either ... now what choice do I have left? Getting an old Nokia?
It's about time to see that there's no choice and it's just a duopoly, even from the user point of view.