> Similarly, you can install Telegram, Whatsapp, Messenger, Signal, Element X (which I all have installed besides Whatsapp) and communicate with people available through those application at the utterly tiny inconvenience of having to open that app first.

...and the not insignificant inconvenience of knowing which of these apps each of your contacts uses or prefers. There really is a network effect of most people in a particular circle just using one thing. For US iPhone users at least, that thing is iMessage.