I just think its an awful argument to say let's see what a QB does if you take away his best receiver. 10 time out 10 his production will go down.
Then you said that great QB's "usually" have great WR's. Well Tom Brady is clearly an exception. Because he had Randy Moss for a tad over 2 seasons.
And while he had the one spectacular season, if you look at his other full season with Randy Moss (2009) it was far less productive than any of the 3 seasons he's had since.