I suggest to delete math.stackexchange.com/a/1372198/42969. The answer is wrong because it assumes the existence of f'(0), which is not given. (I found this while looking for duplicate targets of a current question.)
@Peter That it got 72 upvotes is likely due to the fact that it is linked to a highly viewed question (13K views), and both were tweeted. But there may also be external links involved.