While it isn’t the same case in some languages, double (or more) negatives aren’t all that encouraged in the English language. The reasoning is simple: double negatives negate each other, so why not just use the positive counterpart? Doing so will lead to shorter, more concise and less confusing sentences.
Double negatives haven’t always been derided in English. In fact, read many of the old classics up to the 18th century and you’ll find a long tradition of double negatives employed by the prominent wordsmiths of their time. Some double negatives also remain in acceptable use (e.g. “ain’t seen nothin’ yet”), although there are few of them that editors will happily tolerate.
In the recent past, double negatives have leaned towards being too colloquial for use in many pieces of writing. It just doesn’t sound good for a writer to put “I couldn’t find nothing to exonerate him of the accusation” when putting together a feature for a major magazine.
Because of today’s emphasis on short, easy-to-understand text, double negatives have become doubly frowned upon. That’s because they make it impossible to scan the text. Quickly gloss over a double negative and you can totally get the opposite message of what the writer meant — not the most efficient way to write in the digital age.