That's probably because you haven't spent enough time trying to understand the intent of the expression.

Benevolent here refers to the intent, not the outcome.

If I say "women are so caring" and then use that as a justification for why I shouldn't hire them, the result is a sexist policy with a benevolent origin.

You see this all the time with stereotypes - queer men are so good at fashion, Asians are so good at math, Black folks are such good athletes, etc. We might think these are compliments, but when they are used to deny opportunities they can be as harmful as any other stereotype.