Irrespective of the public back & forth between Docker and CoreOS, that's a completely reasonable stance to take. Standards need to be proven in the real world

Irrespective of the public back & forth between Docker and CoreOS, that's a completely reasonable stance to take. Standards need to be proven in the real world before being adopted. That's why the ANSI and ISO standardization process takes so much time (EDIT: or at least, one of the reasons). When you write "standards" without implementation, what you get is the Object Management Group, which published spec after spec that are impossible to actually implement.