It's an argument against all acts of self-determination, isn't it? It's what the French said in Algeria, well, for a while, that Algeria is French, and 'united we stand'. However, the Algerians had other ideas. See also the USA.
Another point - the stronger power often says 'united we stand'. This has been the Russian (and Soviet) argument for centuries, that the little countries such as Latvia, are much better off under the Russian umbrella. Again, the Latvians may disagree.