The Grammar Debate: Can we have some common sense please?

So my younger brother is what people call a "Grammar Nazi" (although I'm not too keen on the terminology). He absolutely relishes the chance to correct anyone if they try to qualify supreme adjectives, like my mum when she accidentally said "very empty" and gets really annoyed when someone says less when describing a countable noun when they should say fewer. This is all very well and good, but the problem is his strict adherence to the rules of grammar and his usage of it for superiority. As an English student, this obviously gets to me...

Correct grammar and spelling are important, they maintain our coherence and prevent language from spiralling. Of course, the influence of different dialects has influenced this, causing words to change their usage: "Where's me book?" for example. But for the most part, people ARE aware of correct forms and uses. Those of us who do use formal grammar on a regular basis, however (I myself have lost most dialect forms having lived and studied in at least three different English counties) can still be caught by these adamant rule-enforcers for perfectly acceptable forms, simply because they are not following the code to the letter:

Me: It doesn't matter. It will take us less than five minutes to get home.

Brother: It's fewer. Fewer than five minutes.

Now, in theory, he's perfectly within his rights to correct me here, but in practice, there is also a logical justification for using "less" in this context. He believed that because it was a quantifiable noun, that "minutes" should always be referred to as "fewer". Fine, I'll agree to the theory. However, in my own opinion, "less" is perfectly acceptable because although there were five minutes in question, that time period itself is a single entity, it is one seamless stretch of time. It can be divided, but cannot be split as time will continue regardless of when one minute ends and the next begins. A perfectly logical conclusion to explain a now common use of this particular structure, no? Apparently not. After being shot down about this, you can imagine how it made my blood boil. I am not advocating the use of the word "less" to replace "fewer" in all cases. Saying "less people" is not comparable to "less time" as it assumes that the people concerned could be amalgamated into one mass.  

I like to think that I speak and write very well. Admittedly, under the influence of tiredness, nerves or duress, I find it hard to string sentences together, but in general I am completely coherent and speak with correct grammatical structures. But as a student of the literature that encompasses this language, I also understand that a certain flexibility is required. This is not to say that we should abandon our grammatical principles completely. They are important, but as with all languages, there are exceptions to these principles. The French have a body known as the Académie Française, which acts as the official regulator for the French language, and from what I can tell, if we had a similar institution in our country, they would officially recognise certain forms such as the one I used and set the record straight (although with Michael Gove at the helm, I wouldn't hold my breath)

So to all those Enforcers out there: You can carry on removing unnecessary qualifiers, and changing them when they really are wrong. Go ahead and fix my spelling and tell people where they've used the wrong form or "Your/You're" or "Their/They're/There". But I ask you, no, I implore you to remember that there can be perfectly logical exceptions. Our language will evolve and require things to change, so I advise you to use your powers for good, not simply to p*** off the rest of us to feel good about your "superior" language knowledge. It's called common sense. There are structures that should be corrected and others that are acceptable, so learn to know the difference, please.