Because when you give most people the choice of convenience vs privacy, they'll choose the thing that they can feel 99 times out of 100(convenience ). Most people don't care about metadata because first of all they have no idea that's even a thing, let alone what it does. And they're not visibly affected by it. The difference between using signal and Whatsapp for the vast majority of people is the fact that one is green and has everyone you know on it and the other is blue and nobody besides me uses it.

But, if you give signal the convenience of being able to use it with everyone, then the choice becomes "do I wanna use this app that my friend is saying is spying on me or do I wanna use the secure, hacker app?"

And hopefully, more and more people will switch and we can be rid of fucking meta