I think the E6B contradicts the article's assertion that the last slide rule in the US was made in 1976; when I was taking flying lessons a few years ago, I was required to buy a new E6B, and I doubt that was from some massive overstock in the 70's.
True. ASA still makes them but I suppose the only reason they're still made is that it's been considered standard classroom equipment for the past 70 years, combined with the well known universal dislike for change in the aviation world. I don't know anyone who kept using the E6B after getting licensed.
