Solarpunk

I have. I would probably use my last phone for at least another year if it didn't loose system updates. There's too much important personal data (bank, photos, messages including medical info...) on the phone to risk using it unsupported. At least to me it is not worth it so I try to buy a phone with reasonably long support and buy a new one soon after the old one looses support.

I have. Multiple times.

Some of my banking apps will refuse to run on older phones as well.

I've worked at companies where security would refuse to let people run the company workspace on an older phone. So if people wanted to work from home, or check the email from the phone, they needed to upgrade.

I do agree, for most people, battery life is more impactful before security runs out. But if you replace the battery, then security becomes the limiting factor

This will have an impact on companies issuing Android phones to employees, which may be required to use an actively supported device for security reasons.

My phone pushes over the air updates every couple of months. These have included android 13 and 14, and various patches.

Android updates aren't something you have to go and get, they come to you. Having the long term support means your phone will always have the latest user features and security improvements, even for non technical users. People can and do install these all the time.