I think the parent's use of "big boy" was ironic; if someone is patronizing me, I might say "Listen, I'm a big boy, I can handle it." I don't see it as, necessarily, saying I'm in a class above others. Just that I can handle the responsibility someone else thinks I can't.
Yeah, I wasn't trying to suggest that I'm above designers or anything. In fact, I really respect good designers, because I'm not a great designer and I know how hard it is. However, the article is basically saying "Look, you shouldn't even be writing CSS, you're a coder! Coders code! You should hire someone else to do that!" This just seems a bit naive to me.