>Today, your example eight-years-obsolete install base of Android starts with version 4.2, which occupies 0.8 percent of the market. Instead of hoping that the 0.8% will shrink over the next 4 years, Let's Encrypt should understand that the 0.8% are the sane, reasonable people who realize that their Android devices still work fine for their intended purpose and do not have to be mindlessly upgraded because of mass-me…
The issue here is not due to Let's Encrypt, it's due to these devices, like so many others, not being designed to be maintained for the long term. Solving this problem for 1/3 of Android users is going to help reduce the problem of electrical waste; even if they wear out Let's Encrypt will not be they reason why.
How so? Is www.google.com or www.bing.com doesn't work on those devices?
Why are you putting the blame solely on the devices, completely ignoring the fact that Let's Encrypt is an advocacy group whose sole intention is to make non-SSL-based HTTP obsolete? Keep in mind that HTTP has no reason to ever stop working on such old devices!
Noone's asking for indefinite support of old software. What we're dealing here is intentional device obsolescence, where the SSL protocol -- entirely optional if all you care about is reading text and watching pictures of cats from random anonymous sources -- is intentionally being used in such a way as to not be backwards compatible, by preemptively removing support for the earlier devices?