You just saved me money buying a physical copy of the master chief collection. I hate when that happens to games. Spyro the dragon collection did the same thing only having spyro 1 and i think a portion of spyro 2 on the disc. You have to download the rest.If you're disgusted by that, stay away from playstation one and gamecube.
Or would you prefer halo master chief collection on xbox one where you had to download data from server to even play the game... like some nintendo switch games... even if you bought the retail copy.