I think your logic is somewhat off, as you are considering playstation 1,2,3 to be different, while iPhone 1,2,3,4 are in the same bucket. Also consoles are generally a one per household thing. Phones aren't.
Comparing portables to standalone consoles is problematic anyway, for various reasons. Not least, more than one person can play on a standalone at once...
Most of my friends, with iPhones, have upgraded with each iteration of the iPhone. They would each be counted three times, were we to consider each iPhone iteration a separate platform. However, if we're being honest about the experience being compatible across the iterations, is the triple dipping really fair? Frankly, most of the same friends upgraded because they could (afford to) and need shiny objects and that phone-dropped blemish gone -- "The Apple Way."
I think you were going there, but I had to spell it out.
I can see how they're not as different as PS 1/2/3 but they're definitely not the same device. Steve Jobs would slap anyone who dared say that iPhone1 and iPhone4 were "hardware upgrades with same software and software ecosystem"
Different generations of consoles are completely different hardware architectures completely incompatible.