Once again, even if this is the way things worked back in 2016 there is no guarantee they still work like that today.
You have to trust someone. You're not building all your software and reading every line yourself are you?
While there's no guarantees, Signal continues to produce evidence that they don't collect data. Latest publication August 8th, 2024: https://signal.org/bigbrother/santa-clara-county/
The code is open has had a few audits: https://community.signalusers.org/t/overview-of-third-party-security-audits/13243
This is the whole problem with a trust based system
Can you point me to a working trustless system? I'm not sure one exists. You might say peer-to-peer systems are trustless because there's no third party, but did you compile the code yourself? did you read every last line of code before you compiled and understood exactly what it was doing?
It's absolutely shocking to me that people have such a hard time accepting this basic fact.
What's shocking to me is the lack of understanding that unless you're developing the entire platform yourself, you have to trust someone at some point and Signal continues to post subpoenas to prove they collect no data, has an open source client/server, provides reproducible builds and continues to be the golden standard recommended by cryptographers.
I would recommend to anyone reading this to rely on the experts and people who are being open and honest vs those who try to push you to less secure platforms.
I'll reiterate my statement as you didn't address it.