The logical explanation to me is that most of the Signal contacts shared tend to be for drugs or CSAM trading, so they went for the nuclear approach to make moderation easier.
Backatcha. If it's about twitter, specifically 'x', musk has a lot to do with it...somewhere in the region of 100%. It may be unfortunate, but that's just the way it is. And he's the reason many stay away from it. As another poster asked, why do you (continue to) use it? Similarly, someone (else) is highly likely to mention a certain brand of vehicles but not me.
I’ve never used signal.
No clue about CSAM but I'd really doubt it considering it requires a phone number.
I misread your top post as though it meant Signal was the main source for those things. Sorry for the confusion.