I think it makes sense. Early twenties is college, mid twenties is still considered "just out of college", so you are allowed to waste time and drink. Late twenties is getting older but still "hey, we're still in our twenties".

After that, thirties hits and you can't say that you're fresh out of college, or just graduated a few years ago. I think you start to look back and want some validation for the way your life is going.