Yes, that's essentially what I mean by "shared interests".

I thought you meant something more like pre-existing conditions or contexts, for example, the shared interest of everyone who holds fixed debt in keeping inflation low or everyone who owns land on secure property rights.

What I thought was interesting and different about the black example was that this 'shared interest' could be forced on groups that previously shared no interests by a sufficiently powerful group which decides to treat the previously different groups as the same group - in a sort of self-fulfilling prophecy.