kraster, I'd nominate "arguably" as the biggest weasel word in the Apogee quote. Taken literally, it's a boast: "I can talk in a way that seems to make sense, as long as it never has to be tied to any actual reality." Then, unfortunately, they live up to their boast.
The thing is, an idea isn't necessarily wrong just because someone has tried to use a bogus argument in its favor. For example, you're right about the bandwidth limits of most microphones and speakers, but there are exceptions. And the way something is limited to a particular bandwidth can be more important than the bandwidth itself, as far as audible transparency is concerned.
There really are some other possibly valid arguments in favor of audio circuitry with wider (within reason) bandwidth than we can hear, or sampling rates higher (within reason) than 44.1 kHz. I won't go into them here, but they are for strictly practical reasons in particular situations--not because "wider bandwidth sounds better." The latter claim is widely believed by audiophiles, and it's the kind of statement which can't ever be disproved, so they go on believing it. But there hasn't been any proof of it in all these years, either, and one would think that it could rather easily be proved if it were true.
--best regards