Back in the 1960s and 1970s a series of writers who had no training in linguistics started writing books about proper usage. The news personality Edwin Newman and the critic John Simon put out highly praised books that can only be described as “shrieking exhortations about the evils of prescriptivism descriptivism”. King of the pack (all men, of course) starting around 1980 was William Safire, whose weekly “On Language” column in the New York Times Sunday Magazine was enormously popular and enormously influential. He started as a explicator of political terminology, but took questions from readers who mostly cared about grammar and usage. He knew there was a difference, but not much more, and leaned heavily toward prescriptivism at first. Fortunately, he developed a cadre of actual linguist correspondents who schooled him on his errors. Over time, to his credit, he became increasingly looser in his proclamations. No more “the one best way,” as in older engineering.
The book that set me straight, though, was also published in 1980. American Tongue and Cheek: A Populist Guide to Our Language was by Jim Quinn, a non-linguist food columnist. He used a flensing knife to tear the fatuous off Newman and Simon and other “authorities.”
The real breakthrough appeared about a decade later, when the incredibly prolific British linguist David Crystal turned from writing academic tomes (starting with Systems of Prosodic and Paralinguistic Features in English when he was 23!) to popular books covering every aspect of how language works. The properly descriptivist Who Cares About English Usage? appeared in 1984. I can’t remember anyone carping about his writing, but the other five books of his I own, mostly from Cambridge, besides being very good and readable, were non-controversial overviews of the total language. Pinker followed a few years later. I believe - @Johanna can correct me - that most of the important books on style and usage have continued to be written by actual linguists. The one huge exception was the weirdly bestselling Eats, Shoots, and Leaves by Lynne Truss. The American edition was reprinted word for word from the original British edition and some of its advice simply was not appropriate for this country. It went to #1 anyway. Nevertheless, punctuation is a small subset of usage.
Cambridge Ph.D. Guy Deutscher wrote an amazing deep look at the history of words used as intensifiers in The Unfolding of Language. Many common English words include former separate intensifiers as morphemes; undoubtedly this will continue and future speakers will not even recognize “literally” as anything other, maybe on the order of abso-fucking-lutely. There’s a great recent book that reveals how spoken English especially has turned fuck and its derivatives into a new class of words that no longer conform to the basics of English grammar. Fucking as an intensifier has become so common it might not be obscene in a few more years. I’m hoping the book isn’t McWhorter’s Nine Dirty Words. I thought it was The F-Word but that’s a different work. Can anyone prompt my memory?
The latest book I remember reading was Says Who?: A Kinder, Funner Usage Guide for Everyone Who Cares About Words by the uber-permissive Anne Curzon, who is farther out on the scale than I am. She’s never met a locution she doesn’t support. And she has particular hatred for the more presciptionist Dreyer’s English: An Utterly Correct Guide to Clarity and Style, which is funny since Benjamin Dreyer enthusiastically blurbed her book. For credentials, Curzan is the Geneva Smitherman Collegiate Professor of English Language and Literature, Linguistics, and Education and an Arthur F. Thurnau Professor at the University of Michigan, where she also currently serves as the dean of the College of Literature, Science, and the Arts.
I’m having fun, but I hope I’m making a serious point. Usage and/or style guides have a place. Many people lack confidence in their writing skills and want to have some firm “rules” to latch onto, probably because American education for most of the 20th century relied on teachers creating rules that were broken only at a student’s peril. Theodore Bernstein, head copyeditor of the New York Times, wrote a series of books based on the paper’s style guide that were lighter in tone than Newman or Simon. One of them was titled Miss Thistlebottom’s Hobgoblins, Miss Thistlebottom being the archetypal old mail English teacher who rapped students’ knuckles if they constructed a sentence using one of pet peeves. He tried not to be that old-fashioned, but his 1971 advice would appear hopelessly outdated and pedantic today. (From memory: Balding: there is no such word as balding; use baldish instead.) Strunk and White remains a perennial seller not because it is perfect but because it is short and helpful, all that most people need. Please remember that Strunk wrote it because of its dire need by his freshman English students at Cornell. In 1918.
English has changed every year since 1918. English usage has changed every year since 1918. Books about usage need to change every year as well. Guides are helpful; rules are not. Nor is formal written language all there is to English. Almost nobody who reads these books are writing formal English. English, any and every language, as Crystal did such a good job at elucidating, is composed of hundreds of overlapping constituent parts. Linguists should be the only ones addressing these, IMO; too much technical knowledge is needed.
Not every professional is equally good at popularizing. I’ve thrown at the wall too many books by experts in their field that are nigh unreadable. As a popular and non-expert writer I can’t stress too highly (a phrase discouraged by many style guides) that popular works are not what experts do for a living. They are a gift to people who are not also experts in the field. No book of words can convey quantum mechanics. No book by Lynne Truss can replace a thousand-page tome on English grammar. Nevertheless, popular works are critical to what is usually called an educated populace. I find some rock rockstars unlistenable, but I wouldn’t want to do without the breed.