The Apple XS just got a new OS version. The Pixel 3 from the same year doesn't even get security updates anymore.
At the end of the day despite what the Lineage OS flashers will insist, lay-people want updated features. Give them updated features for their old phones and they will keep them longer. Keeping them longer is the most you can do when throwaway tech is the norm.
If you need empirical evidence, 5 seconds looking at any market for used phones reflects that.
