The debates on this forum remind me of Sayre's Law: "Academic politics is the most vicious and bitter form of politics, because the stakes are so low."
... "low stakes" is relative: Spending a good part of your savings for your recreation is a serious thing to some (including me), and for professional photography it's worth money and concerns your future to have an edge.
It is but we're getting to the point where differences are getting so razor thin, such as sensor test scores, 51 vs 61 AF points, etc... You give a professional photographer a 5d3 and top of the line lens and a D800 with equivalent lens or even a 1dx and D4 or D3s for that matter and lens, print all at 16x20, I doubt you will be able to tell one from another. Heck i'm up for that... Anyone want to mail me all those cameras and lenses for testing purposes, i'm willing to test and get back to you all with the results =)