There's often this belief that witchcraft has universal tenants or concepts. There is no real such thing as a "generic" witchcraft without condensing all witchcraft into a colonized idea of what witchcraft is "supposed" to be. If it isn't Wiccan, then it's White. And even then, it's usually bastardized without sources.
Almost everything is anglo-centric unless you look into specific vocabularies and jargon of specific cultures you want to study from, which is difficult when some of us come from nonwhite or non-WASP backgrounds.
I always found it to be better to research specific practices of occultism, witchcraft, spirituality, "superstitions" and folklore of specific regions and time periods.
Additionally, gentrified witchcraft I've noticed comes with the idea that witchcraft is inherently tied to a specific definition of nature, and that humans or human intervention is tainted or sinful somehow.
There's this interesting fetishization for "celtic" (specifically Irish and Scottish, as the other celtics are forgotten or ignored) in tandem with this idea that because media depicts them as Very Green (literally green grass plains), they therefore must be The Most connected to Pure, Untouched Nature.
I've always had a bone to pick with the idea that witchcraft is inherently about "nature" as if cities and people aren't also part of nature, or that all human advancements are grotesque, or that the only advancements allowed are things that are as raw as possible.
It starts to sound like the old discourse of citrine being "not real" because it's often colored via human intervention, or even more extreme anti-GMO and similar discourses, that because humans intervened with something it is now "tainted" which more or less just sounds like Catholic Original Sin with extra steps to me.
Divorcing people from nature while simultaneously noble-savaging Irish, Scottish, and Indigenous peoples does no one any favors in witchcraft and occultism. Everything comes from nature because there is literally nothing else But nature and the things we extract from it.
A lot of these cultures mixed, you're going to find bits of X, Y, and Z cultures kind of mixed together naturally, either because they happened to be similar, live in similar environments, or simply because they are neighbors and maybe one person married another and they mixed their cultures. Sometimes, you're going to find aspects of mixed beliefs, such as colonization giving way to certain aspects of syncretism. So while I don't think there's anything necessarily wrong with mixed witchcraft books and resources, it's frustrating that people seem to believe there is an actual, identifiable universality to witchcraft.