You think you would do something different here? And you have considered all the possible ramifications of doing so? No doubt you've considered the impact on the number of spammy/scammy interactions that everyone experiences, the number of harassing messages that people around the world receive and you've made an informed trade-off between that and meaningful social interactions people have with the folks who find their wallet.
Seems like a pretty strong statement to call it a dark pattern, implying malice, when it could just be a good thing.