Without English majors who’s going to teach kids that them and their are singular?
My "English" teachers never did a very good job teaching formal grammar. It was my 10th grade German class that forced me to learn formal grammar. It was necessary to master both English and German grammar to get the concepts right. In recent years, my study of Welsh, Gaelic and Japanese was more successful with an understanding of formal grammar and how each language is structured.
Beyond grammar, the literature in each language embraces cultural constructs. Michael Savage was right about borders, language and culture. It's important to learn those constructs to successfully interact with with a given nationality/ethnicity in a context they understand.