Why is so much academic writing terrible?

I’m attempting to read an academic paper on the way sexism and racism were intertwined at the time of slavery. At least, that’s what I think it’s about. The paper has a lot of potential to be very interesting, but it’s ruined by obscure terminology, superfluous words and poor sentence construction.

Here’s an example sentence to illustrate my point: “What needs to be discerned through these ideological complexities is that the cult of true womanhood resolves contradictions in the sets of social relations in which women were located.” A potentially interesting topic drowned in poor writing.

So, my question is this: when most Academics spend a great portion of their time writing, why are so many of them so bad at it?