The natural result of that train of thought is that economies of scale, left alone, will result in monopolies for everything. Yet, we don't see evidence for this in the real world. Standard Oil, the poster child for this kind of thinking, had, at it's peak, only 88% of the refining market. By the time the regulation came through, they were down to 61%. How to explain this?
I don't know whether this is true, since you didn't provide any source
its intended to critique socialism but its actually literally the exact same phenomena at work that prevents companies from growing too large.