The UK has one of the largest economys in the world.
Has an above average population.
Has global economic and territorial interests.
has treaty commitments world wide.
maintains a diplomatic network that is second only to the United States (who only beat us cos they are the only super power.
Is one of only 3 (maybe 4) coutries that can project power (for good or ill) interntationally.
You can call that being one of the boss countries is you like.
I tend to take the view that with power comes resonsibility.
And with great power comes great responsibility. 
But is that is the unspoken argument, then does that mean that the nat argument is that Scotland doesnt have anything to offer the world in way of leadership?