In order to reconcile this, we can add layers of privacy, or even holistic solutions, but this incurs greater costs and processing. When we interact over Signal, the only privacy link unsolved is the network traffic analysis between users and Signal itself.
Why do we need bridge-and-interact? L1 transaction costs are high and slow, transactions on an L2 require an operation to bring funds over, consolidating these steps into one makes the user experience slightly easier.