Or anyone who, like Nietzsche, doesn't at least state their reasoning.
Nietzsche isn't 100% correct all the time. As such, you need to bring your own judgment. You are now relying on your own judgment, not big N's, meaning, why are you reading Nietzsche? You're wasting your time. Apply your own judgment to the issues directly. Reading such things primarily gives your judgment a chance to accidentally falter; you're introducing new opportunities for error, not new opportunities for insight.
When someone states their reasoning or - wonder of wonders - includes evidence, then you can at least compare your reasoning to theirs. The parallax is revealing. You can check their evidence against your own warehouse of evidence.
The primary reason to leave out reasoning is to sneak in a lie. "Oh yeah, I don't have any logic or experiment to back this up. Believe me anyway." Hmmm... no.
When someone includes no such things, there's no way to tell when they're sneaking in a lie. They are indistinguishable from someone who is just a liar.
When Nietzsche or others like him state a true thing, they're probably still lying. A fact got accidentally mixed up into their Sophism and propaganda. Oops, haha!