

They aren’t very useful for much besides hobby projects. Modern hardware is more energy efficient and will be cheaper in the long run compared to anything that would be considered e-waste. The only advantage an old laptop has is the initial cost, so it makes sense for a small home server.
That’s only true for the high-end Pi 5. Lower-powered models like the zero 2 are still cheap, and they’re a lot easier to find than a few years ago.