theNetherlands

Signal can update the client to reveal your social graph, sure, but right now, Signal technically cannot know your social graph. And there's two additional layers that make that more likely, which is incentives: being a non-profit, they have no shareholders that would push them to try to look into them, and their primary selling point being privacy, they also have more to lose by doing so. Neither of those apply to WhatsApp. Oh, and a third one: they'd have been in contempt of court, which specifically requested access to such data, and Signal did not provide it because they were not able to.

(I will also say that, in a decentralised communication system, you are reliant on every party you communicate with, and the tools they use, to not expose such data about you either. It's not a panacea.)

Again, it my not be as big a step forward as you'd like, but it's utterly ridiculous to claim that this is not a way forward.

And given that it's not unlikely that larger steps forward may not be possible at all, or would be reliant on us collectively taking smaller steps forward first, I would definitely reconsider putting active effort into discouraging Signal use. Especially if you're not putting at least a multitude more effort into discouraging use of the incumbents.