Google isn’t building an software/hardware ecosystem, it’s building an ad empire. It justs needs its footprint calling back home on as most devices as possible. I don’t think it ever cared about which android version is highest (except for PR)
this is how Android has been forever. Jellybean was the most popular until around Nougat.
People keeping their phones for a longer time shouldn’t be considered a bad thing. Cheap brands using old versions isn’t good though and that does represent some of the numbers.
I feel like at this point Google should ditch the annual OS level-up. Phones and their OSs have matured and pushing out a new version every year is just increasing the support Google has to provide without much benefit. I was running Android 9 until recently, and while I’m now on the 14 beta, I could easily see my current phone lasting long enough to outlive the current 5 years of security updates promised.