And I'm totally on board with that argument. People read fantasy (and let's face it, steampunk is fantasy) to explore and enjoy another world. People play fantasy RPGs to be heroes in their own fairy tales. Being a TB-stricken denizen of a city's slums is seldom heroic, being a farmer is not all that exciting, and usually if we see one of those people in a fantasy novel they're either supporting characters or they get ripped out of their unpleasant/boring lives and thrust into the plot, in which case they're no longer the people they were. So of course most of the protagonists in steampunk stories are aristocrats, Wrench Wenches, stodgy yet solid bourgeoisie, or plucky proletarians who are on the make/on the rise. You want to have heroes the reader can identify with, after all, and most readers aren't into reading about losers.
Which is why Chivalry and Sorcery never caught on. People didn't want to deal with the filthy, disease-ridden mess of the actual medieval period any more than they want to eat actual rats on a stick when they go to the RenFest. And the same is true of the Victorian Era.