It doesn’t stop working at all. It stops getting free OS updates, presumably because there are many dozens of hardware configuration to manage, and having fallen into that trap once with Android devices, they didn’t want to immediately jump into the same pit a second time.
> It doesn’t stop working at all. It stops getting free OS updates
No security updates on a browser (a program designed entirely for pulling and running/rendering arbitrary code and data from untrusted sources) is a death sentence.
> having fallen into that trap once with Android devices
Google doesn't maintain any Android devices except its own.