Fewer subtleties make for less effective writing

It may only have been I and six other pedants who stopped to worry about whether when Finish claims its dishwasher powder uses less chemicals, the company actually means fewer chemicals.

Less chemicals means they use the same number of chemicals, but a reduced quantity of each.

Fewer chemicals means the number of different chemicals they use has gone down (but the quantities of each may have stayed the same, or gone up).

The trouble is, so many people use less when they mean fewer, it is difficult to trust Finish's copywriter. I (and probably only I) am left wondering whether it uses a smaller amount of each chemical, as they have written, or it is using a smaller number of chemicals but their copywriter has been casual about word use.

One of the great authorities is William Strunk whose Elements of Style (or buy from Amazon here) has this to say:

Less should not be misused for fewer. Less refers to quantity, fewer to number. "His troubles are less than mine" means "His troubles are not so great as mine." "His troubles are fewer than mine" means "His troubles are not so numerous as mine."

English is a language based on usage. The meaning of words evolves. Strunk wrote his style guide in the 1920s. Today, less is so often used to mean fewer that, arguably, the words are interchangeable. When we cannot be sure whether the writer has understood the subtle difference in meaning or is simply using the wrong word, what is the point of having two words?

Evolution (even word-meaning evolution) is based on the survival of the fittest. To maintain all the subtleties of meaning language gives us, someone has to fight for precise word use.

I, for one, haven't given up on fewer. So tell us, Finish, are you using less chemicals or fewer?