The first thing I did with my Fairphone was to root it, and tweak the internal BMS/charge controller settings via a terminal. My ~4 year old device battery pretty much still runs like new, still get 2 days of standby.

From what I read on the FP forums though, users running stock tend to swap out their batteries every 1-2 years, like I had to on my old Galaxy S5. Most manufacturers' default battery charge profiles target the longest runtime, causing batteries to really degrade quickly.

For consumers that upgrade every 1-2y they won't notice this issue, but for those of us who want their phone to last longer than that, we notice this really quickly... in these cases having a swappable battery is a must

On the topic of modularity, I had my FP's vibration motor die on me, that was a very easy fix of literally opening up the device, swapping the module, and done. Absolutely love it!