I mean, that's simply not true. In 1955, GM had 576,000. US steel: 268,000. GE: 210,000. If the number of companies with huge amounts of employees has ballooned, well that could easily be a function simply of population growth.
I think the argument you're trying to make is that CEO's of larger companies should make more money comparatively. That may be true (you want the best people in charge of the most people), but you would expect that wage growth to be more linear in number of employees, rather than exponential.
The point is, no C level executive has squared their performance metric, at least not in an individually attributable way, and especially if you consider the negative externalities those "performance gains" have introduced.