Was the whole New Republic fleet meant to be in the Hosnian System?

Just re-watched The Force Awakens, and one of the things that always bothered me about the sequel trilogy is what happened to the New Republic and it's presumably mighty fleet in order for the Resistance to seem like scrappy rebels against the much more powerful First Order.

I'd noticed in Hux's speech before the destruction of the Hosnian system that he talks about the destruction of the Republic and it's fleet: I'd always assumed he meant it's eventual destruction, but it occurred to me that maybe the fleet and a big part of the Republic government was meant to have been wiped out in that attack, which is why the Resistance never gets any support from the Republic from that point onwards.

Maybe this is meant to be obvious, but if so I definitely missed it until now. It also begs the question why so much of the Republic's power was concentrated in that one system.