> Today, it's on Google to maintain dead kernels that it is 
  > still supporting. The 2016 Google Pixel shipped with 
  > Linux kernel 3.18, which was first released in 2014 and 
  > hit end-of-life in January 2017.

This is good. If it is going to take so long to go from kernel to shipped phone, that kernel should be supported for a reasonable amount of time.