It's true that the batteries don't last 6 years, but they are perfectly user-replaceable for someone with moderate technical skills and a few basic tools. Here's a kit that has everything you need:
Is it really that much of a comparison? I think a more fair comparison would be an Android device with a similar update horizon. As far as I am aware, no such Android phone exists.
How is the 6 years (non-user replaceable) old battery holding up?