Bad advice. Signal has its drawbacks, and yet you managed to avoid listing all but one of them. Impressive.
Signal has released an update recently that allows multiple devices (up to 10 I believe). Yes you still need a phone number, but newer commits suggest that is soon to change. Signal has local backups on android, and I haven't heard of any issues restoring from them. Signal is far from perfect, but they are very trusted, battle tested, and overall a better service than what most people are using anyways. By all means, if you have a better service that works for you, go for it, but advising against using signal outright with no alternative is kinda weird.