In Signal's case I think this is just virtue signalling. Considering they require a phone number to register I don't think they're offended by the privacy implications. They're probably just in bed with the Feds and not EU spooks and see a low cost marketing opportunity.

I'll just take this opportunity to recommend SimpleX to anyone interested in a privacy app that's the real deal. They don't require any personal information to use and you don't need to use their servers to transmit messages at all.