I appreciate this very thoughtful reply, Dustin--and I wish we could continue it over a beer (provided that you imbibe). That would be an enjoyable evening.
I think I'm more in agreement with you than not, though I do recognize the reality, not just the possibility, of a culture being "shrunk in possibility, reduced to a set of disembodied gestures — style without substance" and seeing themselves that way. I live in western NC and I have heard members of the Eastern Band of the Cherokee Nation talk very much in those terms. My university has and assigns a "Land Acknowledgement" stating that our university is on land that belonged to the Cherokee; we teach the Cherokee language, have signs in Cherokee, have a program devoted to American Indian and Indigenous Studies; have an MOU with the Cherokee Nation for scholarships for tribal members, etc. And YET, the Cherokee are still protective of their culture: they restrict who can access historical material; it required careful negotiation to include Cherokee myths in an anthology; and I could not walk up and ask to play stickball. It's not because I or others lack real interest or want to profit from Cherokee culture. It's that I cannot fully understand, full stop. What is sacred to the Cherokee will never be sacred to me in the same way, and even my best efforts to represent Cherokee culture will be diminutions of it. That's where the shrinkage lies, as I understand it.
I'm far less sanguine than you about the salutary effects of the Information Age in combatting the erasure of the source cultures from the adaptations. That was the concern of the Ife/Nigerian critics of Damien Hirst's golden bust, I think. They assumed no one would know or credit their culture for Hirst's inspiration; and that no Nigerian artist would have received the exhibition and press that Hirst received.
I find your argument about the lack of an "original" persuasive, certainly in a cultural sense. (In a creative and legal sense, I assume that "originals" exist.) As a classicist, I'm used to reading Latin texts that rework Greek texts, and to understanding them in dialogue with their sources, not as appropriations or erasures of them.
I've been enriched by our exchange and I understand different arguments about the phenomenon of appropriation now. So thank you!