There's a longer chain of trust and research required here. I need to trust the original authors, the authors of whatever Android client I want, the authors of

There's a longer chain of trust and research required here. I need to trust the original authors, the authors of whatever Android client I want, the authors of whatever Windows client I want, and so on. I need to figure out what options are available and why I should trust them and I need to constantly continue doing so to make sure those apps aren't sold to some other party I don't trust. There's no simple mechanism for sharing. Many clients don't support using multiple stores. Even if they did, the UX is never one that I would be able to convince anyone other than a software engineer to use. Single-party centralized solutions offer a simplified trust model and a common auth service makes sharing and recovery much simpler.