[runnerup]

> Are there communities out there where someone being on signal is a red flag?

Absolutely. Outside of the tech industry, people have a "reason" for using Signal. My wife remarked one day that one of her coworkers (a plant operator) suddenly appeared on Signal. I mused that he is probably cheating on his wife. She found out a few weeks later that my hunch was correct.

Other people I've seen on it I've been able to deduce that they're using it for drug purchases (simply by process of elimination, nothing else made sense) even when I didn't already know they were into recreational drugs.

In some circles, Signal is used just for general conversation. But in most, it's not. So being on it is a pretty strong signal that you're doing something 'important' on it...and usually its easy for friends and neighbors to narrow down what that is.

[__MatrixMan__]

You're not wrong, but if we care about privacy isn't that an association that we need to break? Wanting to live in a society where people can have secrets ought to be reason enough to use technology that keeps yours.

And then there's my mom, she's on a grandfathered mobile plan that charges her $1 every day that she sends any text messages. I got her on signal so she didn't have to pay the $1 when she texts me. She got her whole church music group to switch for the same reason.

[runnerup]

Why does it need to tell everyone I have a Signal account?

Adobe doesn't tell everyone that I own Photoshop. Gmail doesn't tell everyone that I have a Gmail email. PornHub doesn't tell everyone that I subscribe to their premium account.

Why the fuck does Signal need to? Broadcast should be off by default, on by opt-in.

[frabcus]

This page gives some details and the technical reason can be inferred:

https://support.signal.org/hc/en-us/articles/360007061452-Do...

It doesn’t send the number to them - Signal don’t get the contact list from your phone. It uses a very clever private contact discovery protocol.

The reason their phone has to know is so that they can then message you. Otherwise there would be no way to message people - a phone has to know who is on Signal to be able to do that.

While the notification could be off by default, since the phone necessarily has to know when your contacts are on Signal for the app to function, it is being transparent about the privacy situation.

Details of the private contact discovery system:

https://signal.org/blog/private-contact-discovery/

[pmontra]

It could be as little as "everybody does it, let's do it too" or they actually thought about it. By signaling to contacts that somebody installed Signal they make it more likely that those contacts use Signal to communicate instead of any other system. It helps the growth of Signal.

Adobe and PornHub don't have the contacts list. Google likely does but maybe they are restrained by privacy laws.