Facebook and twitter are not the same as signal. The signal protocol is a free open source project, that WhatsApp, Signal, and many other use. It secures the data so that whatever servers they are stored on, the company storing it does not know what the texts say. Facebook and Twitter are all about getting as much data as possible. Even though WhatsApp uses the signal protocol, they still collect all metadata with the texts (which is really what they want anyway). Moving to open source project is absolutely the long term goal to get out of this shit hole.