Why can't you start up MP from the MP Disc?

Why can’t you run Matchmaking from the MP Disc?
I ended up selling 5 good re-playable games just for this one because of everyone saying how this games is amazing. I got home put in the disc and while the title screen was loading my cat jumped up on my xbox causing it to shake and my xbox ate through my disc leaving a huge ring. I freaked out of course but after calming down i thought it’s ok i’ll go return it and get a refund. NOPE, they won’t give me any money back. So i thought well then i’ll just play matchmaking while i send the disc to a repair shop. NOPE for some reason you can only play MP on the single player disc and not the MP one, wtf? And then the repair shop said they couldn’t fix the disc because the scratch was to big. So now I’m out 5 games, $60, and i have nothing to show for it. I asked a bunch of people and there’s nothing i can do to play the game i paid for and this sucks.

Thats because there is no SinglePlayer or multiplayer Disc. Its simply Game and Install disc. Game Disc or Disc 1. Is the Game its self. Install Disc or Disc 2 is for the use of Online features, Like the maps, and what not. Disc 2 has no content that would even allow you to play Online. Its just there to install whats needed for MP.