Conversations is only available on Android. And that’s the problem. You need different clients on different plattforms, etc. It’s just a mess. Some clients don’t support encryption and everything is just unnecessarily complicated, especially for new users. You can’t just tell someone “let’s chat on XMPP”. You need to explain to them what XMPP is, what app to download depending on what OS they use, tell them how to set everything up, etc, etc…
Signal is definitely not perfect, but it’s the best known private messenger and doesn’t compromise on privacy and security. It’s very simple to use, the setup process is basically the exact same as on WhatsApp or Telegram, it has good clients for every platform and they have operated safely with a great record for over 10 years.
I understand that other solutions might be better in theory, but if we keep suggesting a new obscure and hard to use messenger to noobs, they will never make the switch. In order to get more privacy for ourselves and the (potentially less technical) people we need to communicate with, let’s just get them to use something simple and private like Signal.