"Kind of harsh" is an understatement. Insulting the reader like this is not acceptable. Mathematics is already difficult enough to learn by its very nature.

"Kind of harsh" is an understatement. Insulting the reader like this is not acceptable. Mathematics is already difficult enough to learn by its very nature. Authors, you don't need to help make it more difficult. We already have a hard enough time convincing people that they can learn something this difficult.