I still keep a couple of my favorite old smartphones. Sometimes I use one of them as my primary device for fun. Phones are among the fastest evolving markets, even a year makes a whole lot of differences. One of the biggest challenges with using old phones is the software: they don't run modern software. And old software isn't compatible with new websites, frameworks, encryption standards, APIs. Use an old device, and you will find yourself unable to get anything done. Every app crashes or complains that it can't connect to the server. Even with Apple who is doing a fantastic job of keeping their phones updated, you may notice that many sites and apps have started dropping support for the iPhone 5, which is still a totally capable device.