Earlier quoted context omitted.
> If you don't trust the people in your chat, they shouldn't be in your chat. I assure you, none of these people trust each other. Backstabbing is normal. They're also likely using it to talk to foreign counterparts. Again, most of whom they don't trust a bit. Encryption isn't just about "do I trust the recipient".
You are conflating levels of trust. The trust level required with Signal is, "do I trust the people in this chat not to share the specific communications I am sending to them with some other party whom I do not want to have a copy ". There are many many situations where this level of trust applies that "trust" in the general sense does not apply. It is a useful property. And if you don't have that level of trust, don…
Because all it takes is one user to decide they trust the third party.
Right now you actually have to do more than trust everyone, you have to trust everyone they trust with their chat history. Which already can include this sort of third party.