The latest released version of Android was 6.0.1 in December 2015 not 5.1 as stated in the article which of course highlights the delay in getting this software out beyond Google Branded devices. My test devices, a Nexus 7 2013 and Nexus 9 updated over the air but all my other Android devices languish on whatever the manufacturer deems the last supported version even though Cyanogen can often offer later releases which seem to work just fine.
What is incomprehensible to me is Blackberry releasing their first Android device on Android 5.1.1 AFTER Android 6.0 was available. Such a major market shift needed to be totally current to have any kind of chance. I just could not imagine Apple releasing a new iOS and then afterwards saying 'here's a new phone with the older iOS'. This release timing probably doesnt seem to matter to people buying in shops. But it affects the device lifetime which is lessened because of it and contributes to Android Landfill.