demonstrably incorrect, it is very easy to find apps with "last updated" dates 2+ years ago. Paid example:

https://apps.apple.com/us/app/a-dark-room/id736683061

I was not asserting there's a rule where you're cut off after 2 years. I'm saying it does happen, I'm sure it's happened in some cases within months of releasing an app that someone needed to update it because a new rule made it not-compliant.

Can you find a single app that was released at the launch of the App Store or Android Market, and was never updated, that can be run on a modern device?

Plenty of desktop software released at that time can still be run on modern systems. Smartphones aren't the same, keeping up with modernizing is a never ending task.