"descriptive grammarians (who describe language as actually used) point out that this rule does not correctly describe the most common usage of today or the past and in fact arose as an incorrect generalization of a personal preference expressed by a grammarian in 1770."
You removed the discrete units from the text ("Brits") and then made a point that holds true only when discussing comparisons that do not have discrete units.
7 is less than 9. But 7 Brits are fewer than 9 Brits.
