Huh. "Decimate" originally meant to kill one out of every ten persons. Nowadays, in everyday usage, "decimate" means pretty much to utterly devastate. Whatever words once meant, the meanings of words is how they are actually used by the people speaking and writing them. Etymological purists may not like it, but what can one do?
"Antisemitic" means prejudice against Jews. I have never heard the word used to mean prejudice against a larger group of people. Heck, outside of the classification of certain languages in Northern Africa and Western Asia, I don't think that I have ever heard the word "Semitic" actually used in conversation as a label for
people, except in artificial conversations about the meanings of words (like this one).
Computers have cut-and-paste functions. So does right-wing historical memory. --
Rick Perlstein