That's certainly notable, but not interchangeable with this one. The total size of your economy reflects certain opportunities for scale, regardless of your population and/or productivity.
If we think about corporations, when you have certain purchasing power, you can extract certain concessions from your vendors regardless of how many employees you have. When you manufacture and ship a certain number of products, you can profitably invest in infrastructure, again regardless of the number of employees you have.
I feel that the same argument extends to trade on the scale of countries. Which does not devalue the milestone you describe, just that they have different consequences.