It's what people are being asked to tell each other. Less than 10 days ago, London banned people who live in different households from meeting each other indoors, to stop the spread of the coronavirus.   "Nobody wants to see more restrictions, but this is deemed to be necessary in order to protect Londoners' lives," London Mayor Sadiq Khan told the London Assembly.   Taking away the welcome mat is key to cutting off the path of the coronavirus. From the beginning of the pandemic, cities, states and countries have banned each other. And now, eight months into lockdowns that have led to immense stress and fatigue among people, some places around the world are introducing even more draconian measures.   The path toward recovery continues to be inherently antisocial and runs counter to how humans interact, live lives, and conduct their business. This unwelcome policy — which has already harmed families, societies and economies — has the potential to lead to a tectonic shift in how the world functions in the foreseeable future.