I get it for Matrix, but Signal really has had the same user experience as WhatsApp for years now. But anyway, your point still stands. That's why user-friendliness is an important part of security (and why Signal work is so important regarding secure messaging apps).
I think it is still impossible to backup one's own messages in Signal and then retrieve them back in another phone. It was possible on Android via root but basically impossible for unrooted phones which is a dealbreaker for Apple devices my friends and family use.
Signal has to provide 100% of the features and convenience of Whatsapp and some more without compromising security for it to be a viable alternative.
At most a little over one year ago, I installed Signal Desktop to open a link in a message I had received on my desktop. This is, apparently, deliberately unsupported, since the app claims that "[f]or your security, chat history isn't transferred to new linked devices". So no, the user experience of WhatsApp is miles ahead of Signal, at least if you want to use a real computer.
