> Using correct terms helps to communicate effectively. What is wrong with promoting correct use of English?
As has been mentioned elsewhere, language is constantly changing. It isn't even that slow of a process. As a result the vast majority of linguists view linguistics as a descriptive rather than prescriptive science. The "prescriptive" approach to linguistics is much more common among teachers but hopefully that is also being tempered.
The reason why this matters is because prescriptive approaches to language have a long history of being used to enforce class, ethnicity and geography based discrimination.
I think there is a fine line to walk here. If you are going to fight against the changing of language, you need a good reason. I personally really dislike the confusion of "literal" and "figurative" (where "literal" now figuratively means "figurative") because it clearlt reduces the expressivity of the language. In contrast, the advent of "irregardless" doesn't reduce the expressivity of the language (though it foes add some minor complexity as it is an annoying exception in the meaning of the "ir" prefix.) Similarly, the common use of "me" instead of "I" in "and" clauses is commonly touted as a misuse of language even though I have never encountered as usage where it added ambiguity and is extremely common. I've had people tell me they take it as a marker of low intelligence while those same people will make a very similar mistake by switching "me" for "myself" in and clauses.
I do think there is value in teaching people about the historical and cross-cultural uses of language, as this increases our ability to understand eachother. I also think there are times where we should push back against language shifts that descrease the effectiveness of the language. However, I think it has to be done with care to avoid perpetuating injustice and becoming irrelevant as the real language in use shifts.
In your particular case, you seem to be denying the existence of fairly commonly used phrases that don't actually have any negative impact on the information carrying ability of the language.