Cultural appropriation isn't a binary, all-or-nothing thing because culture, like most other human inventions--food, language, "race", history--it exists in degrees and gradations that don't neatly begin and end in clearly defined positions.
Usually, when people write about topics like this, there's a big "I know it when I see it" attitude, where, for clarity's sake, the author takes an extreme example and says "This is wrong." For example, they might show a picture of Paris Hilton (she's still alive, right?) in blackface and a dashiki at a Halloween party to illustrate the problem.
But what about when the lines blur and things aren't so cut and dry? What if the person just likes hedscarves and bright colors that might seem vaguely African-inspired? Or, moving past fashion, should white people not enjoy or appreciate black culture, too?
This isn't a minor gripe. There is some seriously conflicted messaging going on in our popular discourse on how whites are expected to engage with black culture, because there's often the presumption that the white person *has* to have some sinister, ulterior motive beyond simply liking it.
I've heard some black people who grew up in lower-income areas (I THINK Ta Nehisi-Coates said this, but don't quote me) talk about how alienated they felt reading books as a kid because it was a sign you were "acting white." They weren't allowed to enjoy Shakespeare or Faulkner because they're brilliant authors because everyone around them assumed it was a form of virtue-signalling.
The same thing happens with white people that enjoy things pioneered by black people. You'll hear it on both sides, from whites and blacks, the left and right, progressives and regressives: You're only pretending to like that to impress people.
This is a really touchy, complicated subject without clearly defined boundaries, but we have to work on clarfiying them nonetheless if we want to move forward.