I think there might be a few reasons TB.
I think # of players per team is one consideration. There are 40 players on a football team and that helps make the sport more segmented and appear more as a true team sport IMO becuase you can not be carried by one player as much.
In Hockey an Elite goalie who is always on the ice can make a bigger difference and can have stats measured entirely to his play.
A pitcher vs. hitter battle is a individual one on one battle at many levels although there are other players that can effect his stats for the most part the stats are relating to his performance. An error in baseball doesn not count against the pitchers era for example.
In Football it is widely understood that when a team wins the QB usually gets the credit and accolades and when a team looses the QB usually gets the negative spotlight as well, is it fair, maybe-maybe not but it comes with the territory.
I'm not really sure what your question is though. Is it are you wondering why the QB's are measured in Wins and losses? If so, I kind of see you point but with it being more of a team game in Football I think that is just not someting individually measured in Football - except for maybe head coaches because for them the is about the only measureable stat.