@domubpkm The majority of devices are eol after two years, i.e. they lose support from the manufacturer for Android updates and security patches even though they are still viable hardware wise. LineageOS, UT and others fill the gap to stop these devices going to landfill and quite rightly so.
The Nexus 4 is a great example, a nine year old device that still going with UT and has a really good battery as some are dated 2013 and still bhold a good charge.