Why is 2 Channel better than multi-channel?

I hear that the music fidelity of a multi-channel AV Receiver/Integrated amp can never match the sounds produced by a 2 channel system. Can someone clearly explain why this is so?

I'm planning to upgrade my HT system to try and achieve the best of both worlds, I currently have a 3 channel amp driving my SL, SR, C and a 2 channel amp driving my L and R.
I have a Denon 3801 acting as my pre. Is there any Pre/Proc out there that can merge both worlds with out breaking my bank? Looking for recommendations on what my next logical steps should be? Thanks in advance.
look at my system I just finally posted the pics tell me what you think about my 5 channel setup.
"Why is 2 Channel better than multi-channel?"

'Tain't. Music arrives at our 2 ears from all directions. Five channels gets it lots righter than just 2.
The next logical step for this guy is a better AV pre/pro, perhaps with "dirrect analog bypass" for his better sources.
Try an older Krell HTS2. I think this has "throughput's" for analog pass-through...and the digital is unbeaten for DD/DTS and PCM music.
Otherwise, spend less on a more dynamic DD/DTS pre-pro, and do a 2 channel dedicated pre for your 2 channel music(looping the two together).
Music is best (I feel) in 2 channel, but for movies, providing you have good speakers,and Amps all around) in my opinion 2 channel can never,,,NEVER equall the experience of 5.1,6.1,7.1.....true Audiophiles' should come to understand that movies dont fall into this realm, and thus should get on the HT bandwagon, for movies 2 channel is an antiquated idea and format...and ignoring the new technology is doing yourself an injustice....remember we are not AMISH!
Hey Jeffreybehr. With 2 channel, music still arrives at our 2 ears from all directions. And live music *starts* its journey to our ears typically from in front of us, not all around us. So what's your point?