Of course pedants can be wrong.
I have a friend who was a year above Nigel Farage in Dulwich College and he was a copywriter, so he vociferously fancies himself at English, but there have been at least three occasions when I looked something up in the OED and found that he was wrong about something. Indeed the crudest one was when he wrote "he didn't use to do it".
One of the functions of a top English school is not to educate its pupils but to give them a sense of superiority, I believe. They are taught, say it loud, and say it with confidence, and you can rule Britain even when you've never been an MP. (that's very basic social psychology)
I once saw a bluestocking shout down Jonathan Ross on the subject of far farther/further,farthest/furthest. I forget what her exact, supposedly correct version was, but the point was, it had been drilled into her, as had been the belief that she had the right to drill it into others.
I came across it later when I was reading Anglo Saxon. Afaicr, the original forms were the ancestors of "far, further, furthest" (the word doesn't exist in modern German, so we can't use their paradigms for assistance), so that could be deemed "the correct" version (and I try to use that version, as you don't come across as especially pompous when you do). But if you really go into detail with the OED, you'll find that the forms "farther" and "farthest", although they were originally erroneous, have been around for 700 years or more, which seems to me to be sufficient pedigree for them to be deemed "correct". But Google it and you will see people tying themselves in knots trying to explain the subtle differences in the way they claim they use farther and further and so on. And it gets worse if you include the Americans whose source is Websters.