Typical behavior from Signal. They have a track record of hostility that we as a community should really not be tolerating. I do not use Signal and I tell my friends not to, either. Play nice or don't play at all.
goodpoint's answer is probably the best longer term answer: someone needs to fork Signal and manage it properly. But it's not as simple as just rebranding the software, it needs lots of difficult technical work to fix its many problems.
Why is that?
It is not like most of my social groups are me-centric, which forces me to pick battles carefully. Now that I moved people to signal, I need to do what I can to try moving signal to my ideal space ( no phone requirement being one of them, 3rd party clients and so on ).
That list is still short. I would love to be able to return to pidgin days, where all I had to connect my various accounts >.>
I do not know if the issue is that some the features are just incompatible with standards?
Sadly, the biggest problem is inertia.
I used this snap package thinking it was an official one, if I had known that it isn't I wouldn't have installed it.
Threema is liked for security. I haven't used it, but my mother's tennis group is using it, and they're all 65+.