Earlier quoted context omitted.
Rules like these aren't really good guide to style though. They are the sort of guidelines suited to curing teenagers of bad habits. That's the problem I have with articles like these. They aren't adult discussions of language; they do not teach effective writing, and do not promote an understanding of language. One should ideally outgrow such pedagogy by one's second year of college.
In this case, the rule is just not to use the word "very." I can't think of a single context where "very" doesn't degrade from the semantics and syntax of a sentence. I think this rule is appropriate to any and every style.
Or perhaps more appropriately:
"The truth is rarely pure and never simple. Modern life would be very tedious if it were either, and modern literature a complete impossibility!"