The client is made by the same people at the end of the day, so that is of little comfort.
Also, adversarial does not refer to just possibly breaking encryption, it also applies to daily continuity. I trust my ability to keep a small encrypted password database safe more than I trust some random companies to get bought or change their business model and suddenly I have to decide between a massive Flag Day or paying for something I did not have to before or having some kind of other unwelcome limitation placed on me.
I like controlling my own destiny, thank you very much.