I couldn’t agree more! As a manager, executive, and consultant, I would always cringe at tools (like email, Slack, even Trello!) which allow a work item to be assigned to more than one person at the same time. I always say, “If two people are responsible, then no people are responsible.”

I ended up building a zero-adoption task manager startup (http://tribe.do), and you better believe that each task can only be assigned to one person :)