The original typewriters were always jamming as people began typing faster and faster, as the striking mechanisms would overlap. The querty board was supposed to make the really fast ones slow down. It didn’t work however because even on the old non electric units good typists could approach 100 words per minute. My mom was one of them and the speed was remarkable to see and hear.
Cecil himself wrote that this was “not far from the… truth,” but stops short of actually claiming it as the reason for the QWERTY layout.
Wikipedia, for what it’s worth, calls the notion that QWERTY was designed to slow typists down “incorrect,” and states that it was to position the most commonly-used letters as far apart as possible to minimize jamming. This has always been my understanding as well.
(I think this is the column you’re referring to, by the way.)
Oh, and welcome to the Dope, johnnymiami! Hope you’ll stick around.