You're mistaken on the basis of your beliefs here. Signal only had two pieces of data around your phone number (joined datestamp, last online datestamp). This means that governments can't petition signal for any more information, since signal simply doesn't have it to give (by design).

Your point on fb is hilarious, because they do require it. They just don't require you to input it, because (1) they already have it and (2) you freely provide the missing pieces without them even asking. But, like I said earlier, if this goes against your posture, use something like Briar or Matrix or whatever. Choice exists, because everyone is different and has different postures.