Signal isn't nice to use on multiple devices. I'd lose my chats if I lost my phone without backing up the keys. Actually WhatsApp somehow deleted my chats even though I restored my phone from backup, idk. Signal also stops notifying you if it goes out of date.
It's fine for the use case they're meant for. Unlike Instagram, they had these usability limitations from the start, and they delegated auth completely to the phone providers.
