Do you mean they sell phones with the oldest hardware in them?

Because they sure don’t have the longest software support cycle, they only seem to be getting 4 major Android versions. The iPhone 6s and the original SE got what, 6 major iOS versions? Both OSes get annual major versions. And of course, in both cases you get security updates for a few years after the end of new major versions.

You also get lower end hardware with the Fairphone, so that might change your opinion on whether you’ll still want to run it 15 years down the line.

There is plenty good about the Fairphone, like its’ repairability and the fact that they do simply sell you parts, but otherwise, you don’t get all that much bang for your back. Anything that’s called “responsible” or “sustainable” is always going to cost more simply because you can’t pay your employees more without your phones costing more