When did people forget the difference between “less” and “fewer”?

Look, this is not hard: this website explains it. You do not have to be a genius to understand it.

And yet, it seems nowadays that fewer people know how to do it correctly.  See, in that previous sentence–that’s using it correctly.  It would have been incorrect to say “less people”.

Is there less emphasis on grammar in schools?  Again, that’s the way to do it: “less emphasis”, not “fewer emphasis”.

What's your stake in this, cowboy?