You folks on the left just don't know how truly tone-deaf you can be, because you are not, in fact, dosed with unceasing rightist sentiment sanctified as "the center". You live in a bubble of uninterrupted leftist thought, assumptions unchallenged and therefore never noticed. The leftist assumptions made along the way to your opinions about Garrison Keillor are striking.
Some of your quotes:
"He began his career in the early '70s writing short humorous essays for The New Yorker (he later became a staff writer then left, on a very high horse, when Tina Brown took over as editor in 1992). He is probably the purest living specimen of the magazine's Golden Age aesthetic..."
The New Yorker is about as leftist-elite as you can get, and he was too leftist-elite for that magazine.
"How has someone so relentlessly inoffensive managed to become so divisive?"
He's only inoffensive if you snuggle comfortably in the bosom of the leftist elite.
"Keillor delivers the news in a kind of whispery trance. When he speaks, blood pressures drop across the country, wild horses accept the saddle, family dogs that have been hanging on at the end of chronic illnesses close their eyes and drift away."
Your mistake is in never having noticed that the blood pressure of many people actually rises when his dripping-water monotone delivery of leftist humor begins, and this has always been so. The problem is that you seem never to have met any of these people. His cloying adagio may appeal to people who already agree with him, but to those who find his unavoidable politics suspect, the extra time between drawn-out syllables is precious life itself down the tube, wasted, never to be regained. The fact that he takes an hour to deliver twenty minutes of bilgewater does not increase the value of the bilgewater.
There is nothing new in popular irritation with Garrison Keillor. His movie has not uncovered a new phenomenon, and has certainly not caused any American to change opinion of him. I have always loathed exposure to his leaking-faucet radio program. As with any annoying, repetitive, purposeless noise, I move quickly to stem it at the source. I hasten to add that if I were unable to, I might also wish to "close my eyes and drift away", much like a dog with a terminal illness.
I am reminded of an often-repeated story about a newspaper employee, snuggled comfortably in the bosom of the New York Times, who burst into tears upon the election of Richard M. Nixon to the office of President. She could not believe that he had been elected, and refused to accept it at any rate. "It simply can't be true," she wailed, "I don't know ANYBODY who voted for him!" How far is it from the New York Times to The New Yorker?
I am fairly sure, Sam Anderson of New York, that you don't know ANYBODY who doesn't like Garrison Keillor. Pity that. Such a friend could have saved you from writing this article, better entitled "In Which I Demonstrate My Utter Ignorance that Half of the Country Exists."
Garrison Keillor is relentlessly many things, but inoffensive is not one of them. Boring. Pompous. Tedious. Sanctimonious.
He's Michael Moore without the flying spittle.