Yes. Signal should have taken your last sentence to heart and not implemented contact discovery. The feature actually compromises privacy even when used as intended, because anyone can see whether anyone else uses Signal (and, if you check regularly, when they started using it, which can be revealing). The fact that the feature requires sending your entire contact list to Signal's servers (using a broken encryption mechanism) is just another reason not to do it. To add insult on top of injury, Signal doesn't even notify the user it's uploading their contact list, instead using an actively misleading description when it asks for contacts permission ("See contact names and photos in your chats").