User ID over rollups

What if MetaMask was like an email client (ecash client) and sending tokens to other rollups would be something like:
Bob@arbitrum.eth → Alice@optimism.eth
And with text filed stored as Data Filed in the rollup chain. As an option, it could be encoded with a decoding key sent to the user’s regular email.

I see something similar in bitcoin LN getalby chrome extension eg.