Except for the part that it's not a question of trust (being open source), there's no third-party architecture to trust (it can and should be self-hosted), the data on the server are also encrypted client-side before leaving your device, sure.

Oh, and you also get proper sync, no risk of desync if two devices gets a change while offline without having to go check your in-house sync solution, easy share between user (still with no trust needed in the server), all working perfectly with good user UI integration for almost every systems.

Yeah, I wonder why people bother using that, instead of deploying clunky, single-user solution.