To the original question, i would wager the reason they do it in a wink wink kind of way is because they are actually talking about something like movies, programs, games, tvshows, etc... but using "linux isos" as a euphemism.
i reall yhave no idea, but just my 0.02$
That's what i told my isp when they asked me about my bandwith use : i download (lots of) linux isos...