And the phone number is shared with the provider and if I lose my phone number it can be a serious pain to recover stuff quickly. Signal, telegram and WhatsApp are abomignities. Matrix doesn't tie accounts to cellular numbers (God we still are in a world where those cellular are a requirement to sign up to most things). The matrix network is as transparent as it can be, Element is a decent client that runs on iOS, Android and a Web browser.

Element is such a good alternative that the app store appears to be stubly demoting it in the search result, and never seem to show it as a related messaging client. Strange world we live in.

Edit: furthermore, Matrix tech both for the server and clients is entirely open source, and one can spin up its own network.