Comment by Canada

Telegram is great for large groups. It's better to compare Telegram to Reddit than Signal.

Signal is excellent for tiny groups of known participants. I prefer it over anything else for this use case. The group permissions Signal introduced a few years ago are well suited for that purpose. I've recently started running small groups on Signal with about 100 participants who mostly know each other, but not tightly. The recent addition of phone number privacy makes this feasible.

Once you start moving up in scale you really need moderation tools, and Signal doesn't do so well there. When you have thousands of people and it's open to the public you need to moderate or else bad actors will cause your valuable contributors to leave. Basic permissions like having admins who can kick people out and restricting how new members can join only gets you so far.

The issue is that in Signal there is no group as far as the server is concerned: The state of the group exists only on client devices and is updated in a totally asynchronous manner. As a consequence it is more difficult for Signal to provide such features. For example, Signal currently has no means to temporarily mute users, to remove posts from all group members, easy bots to deal with spam, granting specific users special privileges like ability to pin messages, transferable group ownership as opposed to a flat "admin" privilege, etc.

Think about the consequences of Signal's async nature with no server state: What does it mean to kick someone out? An admin sends a group update message that tells other clients to stop including that user in future messages. Try this: Have a group member just delete Signal and then re-register. Send a message to the group. They're still in the group. You get an identity has changed message. These are really only actionable with people who you know... that is, in tiny groups.

And then, the biggest strengths of Signal, which are its end to end encryption and heroic attempts to avoid giving the server metadata, are less valuable in the context of a large public group: Anyone interested in surveilling the group can simply join it, so you have to assume you're being logged anyway. Signal lacks strong identities as a design choice, so in big groups it's harder to know who you're really talking to like you know that "Joe Example, founder of Foo Project" is @Foo1988 on Telegram and @FooOfficial on X and u/0xFooMan on Reddit.