> Approximately nobody is throwing away phones because the OEM stopped providing security patches.

This becomes a practical reason more quickly than you think. If a company only provides 4 years of security updates and they only provide 2 android MV releases, you quickly become out of date. I had a BlackBerry Key2 that I bought in 2018, I had to replace it in 2024 and I was really holding onto it despite a lot of practical problems - Slack dropped support for the version of Android a year earlier, it was only when I tried to install Google Wallet and could not that I finally decided despite the hardware and software functioning fine it really wasn't practical to use a device that was stuck on such an old version of Android. (I would've tried to figure out the kernel myself if the bootloader wasn't locked.)

Phones don't actually get slower, or, they shouldn't, if they are reasonably well maintained. A battery swap might be necessary to preserve battery life under load. A NAND might start going bad.

Apple just shipped iOS 27, which has support for 2019's iPhone 11. So we are around 7 years there. It's probably fine for many people's use!

For a task like openclaw or hermes, or even something more aggressively graphical & GUI, it's not hard to imagine an 8 year old phone doing fine.