Well yes...
I'm no Dickens scholar but I am sure that Dickens did not deliberately present a distorted view. It is more like a partial view. Like our contemporary writers his perceptions were colored by bias but since he was writing for the English middle class it would need to be a fairly accurate middle class perception.
If you are implying that there was a class below Bob Cratchett with an even sorrier lot, you are correct but that doesn't obviate the message to which Tom alludes.