The latter is true unfortunately. Because of understandable security reasons they gave up the SMS integration about a year ago since it's unencrypted and not a good fit to the security standards of signal.
Until there is some form of open interconnection between messaging apps there will be no end to WhatsApp.
Don't get me wrong, signal is a great alternative, but it does not achieve more then it's core value of security, and this will never be enough.
Omg sind wir unerträglich. Aber ja, ich kam um diese Kommentare zu finden oder zu schreiben.