You are mistaken.

I know it's about convenience. That still isn't how whatsapp works.

Using WA you cannot be logged in on more than one device. If you do log in for real, the previous device stops working. All additional devices have to be linked to the first one, and they access the service through that one main device.

You can't use secondary "linked" devices or sessions if the main device is off. Try it. Open whatsapp web, login, then turn off your phone. The web session will stop working until you turn the phone back on, because it doesn't actually connect to WA, it connects to your phone. Only your phone is what is actually connected to WA servers.

All "linked" devices/clients/bridges work this way. All available whatsapp bridge software works by pretending to be an additional "device", and as such suffers all the same limitations.

And Beeber doesn't do anything special, their systems are based on matrix. In fact I'm literally running the exact same bridge software they do.

Edit: Something has changed. This used to be true. Somewhere along the years WA has significantly changed how their systems work. I can only assume they buffer activity for 14 days and somehow defer the synchronization of content with the main client, because all the same limitations of devices being subordinate to a main session apply.

The most mind-boggling is the alteration that multiple client devices are now allowed, but also not really.

And they still require that user history be monolithically stored by the user, on their MOBILE device. And the only way to have a backup is through their backup solution, and god-forbid you press the wrong button when setting up a new device, because not restoring when the one chance is given, means everything is gone forever.

The main reason I use whatsapp via a bridge, is to have my message history stored on a proper server, so I don't have to do the restore backup BS whenever I switch devices. I just re-link the bridge and go.