While I also believe that "on any given Sunday"....any team can win. That said, the Bengals were at home last night, as were the Packers last Sunday. I think most fan mentality is that a good team wins home games, especially against a 2-3 team, playing a backup QB.
I am not debating any of your points, since they are valid. That said, nothing wrong with fans discussing ways that the Packers can improve, which often can come off as "b*itching".
All that said, I sometimes wonder how the current Packer team would be with a Joe Flacco at QB. I do like Jordan Love, but he definitely needs to become a better game manager.