This is a standard response when peevers complain about “bad” English. In fact, it’s appropriate response #1. As you know, peevers file regular grievances about singular “they,” about new words, new meanings, the word “irregardless,” slang, the willingness to end a sentence with a preposition, etc., etc.—anything that was not OK according to their revered English teachers. (Standard response #2 is the observation that whatever they’re complaining about has actually been standard English for hundreds of years, but that’s not relevant to this post.)
Languages change. Everyone knows that we no longer speak Shakespearean English, that the French no longer speak Latin, and so forth (and we don’t complain about those facts, interestingly enough). I mentioned “new words” in the previous paragraph; of course everyone expects that modern versions of old languages, like Hebrew in Israel or Latin in the Vatican, have to add new words for concepts like computer and automobile, so adding new words is not especially surprising. But why would a language lose words?
One answer appears in a beautifully written article by native Yiddish speaker Rose Waldman. (Yes, there still are some native Yiddish speakers! Hasidic Yiddish in this case, to be precise.) Do read the comments at the end of the linked post, even if you don’t also click through to read the quoted article itself. You may think of Yiddish as a dialect of medieval German—if you think of it at all. You may or may not know that Yiddish itself is a language with many dialects. You may incorrectly think that Yiddish has something to do with Hebrew. (Side remark: Yiddish does use the Hebrew alphabet, as in the figure at the top of this post, although the words don’t look anything like Hebrew words. And Yiddish does borrow some Hebrew words; like English, its vocabulary includes borrowings from many other languages.) Despite all that, Yiddish and English are Germanic languages, and Hebrew is a Semitic language. You have to look past the lexical borrowings into the core structure of the language, and the language families become crystal-clear.