EU isn't encouraging the dismemberment of the UK, the Brexiters are.

"A diminished, dismembered British partner is bound to have a deleterious effect." Agreed, but that is what the Brexiters voted for, so we have to respect their decision. 

"There is powerful argument that the EU sucks up too much of the oxygen necessary for national self-determination and fully functioning democracy. " You just contradicted yourself.