In general there is a simple rule: either usability or security.
All general consumer grade tools are fighting with this equation: How can we make an app which will appeal to the broad audience which will be easy to use.
I can't say anything about signal but in general if something is easy to use and you can chat super secure with your grandma then most likely it isn't secure how you might think it is and it's actually an issue because you may want to send data which otherwise you wouldn't if you know you're on compromised channel.
Sharing history between e2e encrypted devices is a tricky thing because you should have forward security with some ratchet keys.
All general consumer grade tools are fighting with this equation: How can we make an app which will appeal to the broad audience which will be easy to use.
I can't say anything about signal but in general if something is easy to use and you can chat super secure with your grandma then most likely it isn't secure how you might think it is and it's actually an issue because you may want to send data which otherwise you wouldn't if you know you're on compromised channel.
Sharing history between e2e encrypted devices is a tricky thing because you should have forward security with some ratchet keys.