I've learned that most of the things that English speakers are taught about grammar are pure opinion and have no effect on the language. Starting a sentence with a conjunction, ending a sentence with a preposition, splitting an infinitive, or using a double negative are things that early British writers decided didn't meet their tastes at the time when the language was just beginning to be accepted as a literary language. They don't have any basis in linguistics or comprehension; they're based on morals and classism. For example, they thought double negatives are illogical because, mathematically, the words would cancel out, so people who used double negatives must be less logical. But there are plenty of languages where these features are used or even required, e.g. Spanish makes use of double negation a lot.