The advice is to not add to the free roaming bird population yet another social space to gather, as birds by nature stay in fairly isolated groups, but will co-mingle outside their flocks with even other species when food sources are extraordinary rich compared to those they’re used to otherwise in more natural settings. This isn’t a new idea, it’s well established and accepted by experts. Don’t add to the problem. Birds don’t just go around greeting every bird in their city/state.