You have no idea what you are talking about. First off many game distributors get games a few days early and are told not to sell until release date. It's the distributors responsibility if he or she sells the game early. My friend is only 20 and owns a small game shop and he has copies of Halo 4 already, but he isn't stupid enough to sell it to his friends. Some other people are however. So Halo 4 is technically currently being sold, under the table.
And reviews use system link and stuff like that?!?!?! Who do you think you are? Why in the world would reviewers test a game on system link? That will not give them the same feedback as 98% of the Halo 4 games who will soon be playing online. Also, why would 343 decide to leave the servers offline until release date? This would create chaos! Servers for most big games are up weeks before release so that they can constantly be tested. The last thing you want are servers crashing the day the biggest game of the year comes out.