I was writing a document in Microsoft Word, and it flagged "less resources" as being ungrammatical and suggested "fewer resources". I did some research, and it appears that "fewer resources" seems to be used more often, and one commenter on another English usage site said this was correct. But this seems odd to me. I try to be diligent about using "fewer" with countable nouns; a phrase like "The software has less bugs than it did last week" just grates on me. But even though "resources" is a plural and thus looks like a countable noun, it doesn't seem as though it should be, logically. If I were to write a business analysis that said "Plan A requires fewer resources than Plan B", would that mean that, say, Plan A would require only 15 resources while Plan B might require 17? This doesn't make sense. But is it possible for a noun such as this to be considered countable, grammatically, even though it makes no sense to use it with an actual count?
In standard grammar "few/fewer" is connected with a plural noun and "little" ( meaning not much) and "less" with singular of uncountables. As a non-native speaker I can't judge whether people in spoken language really observe this rule. It might be that people often use less + plural because they consider this differentiation as impractial for everyday language. English has too many words and it is the only language of the ones I know that makes such an unnecessary distinction.
The funny thing is that French peu (not much/not many), the origin of few, can be connected with singular and plural.
It seems that in the past some grammarian of renown suggested that "little" should be used with singular and "few" with plural and somehow this suggestion became a grammar rule. Actually a rule that complicates the system and I think that people who don't observe this invented rule simply try to make the system easier.
Looking at Ngram fewer resources is a much more used expression compared to less resources.
The less versus fewer 'rule' is total BS. No-one ever has a problem with more being applicable to both count and non-count nouns (e.g. 'more children', 'more whisky') -- why, then, the ridiculous fuss about insisting on fewer instead of less for count nouns? If it were me, I would completely ignore MS Word's 'correction', which has no basis in anything except a stupid rule invented by prescriptivist grammaticasters.