A bit cannot be well, harmful on purpose. (most anyways.)
In some ways it is like saying that bits hurt horses like guns kill people.
But the matter of truth is, people kill people.
In other words, it depends on what kind of hands you have. If you have hard hands, any bit you use, even the most softest its will be hard. If you have soft hands, then even the most harmful-causing bits will be soft. Usually.
But anything can be painful or wrong in the wrong hands.
Guns kill people.
Spoons make people fat.
Pencils misspell words.
And bits hurt horses.