This is a contested grammar rule that was based on one persons opinion in the late 1700s.
There are plently of examples in history where less and fewer are used interchangably. It is not a fixed part of english grammar as much as an “internet gotcha” that is commonly repeated.







Personally I disagree. “Fewer” is more verbose than “less,” so it just looks cumbersome to me in many instances.
It also irks me a bit, because I know at least some of the instances I see are likely based on the above misunderstanding, not taste.