Sure, fragmentation is bad, when you compare it to a monoculture like iOS. However, PCs managed to thrive just fine for decades, and I'm sure Android will do just fine as well.
TVs and washing machines and refrigerators and watches are starting to run their own operating systems. Which OS do you see your TV running? Because I'm pretty sure they'll all be running Android soon.
Did Microsoft allow hardware companies to customize the OS interface? Did Microsoft assign hardware companies the responsibility of delivering OS updates to users? Did Microsoft let hardware companies ship 2-3-4 year old versions of Windows with new hardware?
TVs and washing machines and refrigerators and watches are starting to run their own operating systems. Which OS do you see your TV running? Because I'm pretty sure they'll all be running Android soon.