So, I was never a beer drinker (and I'm currently fifteen years sober after an issue with alcohol in my early 20s), and I wasn't overly familiar with "dry beer"... Part of the reason for that is here in the U.S. dry beer just never quite took off. It is similar to American pale lager, which is the dominant style, but for whatever reason, the American market didn't take to "dry beer", though not for lack of trying. Budweiser introduced "Bud Dry" in 1990 for example (though I don't think I ever saw anyone drink it. It was discontinued in 2010). Michelob also introduced a "Michelob Dry" around that time, but I don't think it even made it to 2000.
As for the stance the manga takes towards dry beer itself, I think it's rather unfair. Some people might genuinely prefer a less sweet beer and so to say that it's worthless is another one of those things that I've just learned to accept about Tetsu Kariya, in that he seems to believe something should only be done a certain way and if it's not done that way, it's wrong, especially if it's different to the traditional way...