Beeper is just a skin over Matrix, and they are hosting and managing the bridges for you. So that when any of protocols they support breaks because the other company changes something (or intentionally breaks things to stop connections from clients they don't want), Beeper fixes it rather than you having to wait for the open source community to do so and you implement that fix. Which who knows how long either scenario will take.

Paying for Beeper is not having to manage the self hosting, which many are not willing to do. Because as with most open source solutions, it's not very simple and is intimidating for many. Not to mention having some box open to the internet, and having to maintain security updates for that box.

I would love for libpurple to come back and make these things relatively simple. But the reality is that companies have walled off their gardens to control the experience, and many other reasons ranging from greed to security to spam mitigation.