Accessing chats from a new device has no technical relation (or constraint) to the lack of end to end encryption. Wire encrypts all chats end to end, and still provides syncing conversations to multiple devices on multiple operating systems. It does limit the sync to the last 30 days, but that’s mostly because of cost reasons rather than technical reasons.
Edit/correction: Neither Wire nor Signal sync conversations that have happened before the setup of a new device to the new device.
Signal also features multi-device end-to-end encryption.
This non-technical argument feels more and more a shill talking point because the claimed constraint is NEVER provided with technical arguments.
However, it feels intuitive to non-techies: "End-to-end means only one end and I have many devices therefore I have many ends so I can't end-to-end with every end, so better not end-to-end..."
If you can view your old conversation from a fresh installation on a new devices then this automatically implies that some 3rd party has access to your keys. I.e. your conversion cannot be considered truly private.
It can also imply syncing over an end to end encrypted (and verified, using QR codes at setup) channel between the devices being synchronised. I believe this is what signal does, for example.
No it doesn't. The sync could be device-to-device, or it could be encrypted in it's storage on the intervening server, and require that the user provide secrets on the new device.
Edit/correction: Neither Wire nor Signal sync conversations that have happened before the setup of a new device to the new device.