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.
Palm got stuck on Sprint and then bought and killed by HP.
Microsoft killed its own chances by not allowing Windows Phone 7 phones to upgrade to Windows Phone 8.
Consumers didn't choose in a free and fair market. The market was already set by the time most had even started getting smartphones.