Keep your rolleyes to yourself. If you had kept read a civics book that isn't edited by Ayn Rand, you would know that there is no "sanctity" of contract law.
The government (ooooo, the big bad government) is the only reason that contracts can exist, and they can (but don't often enough) reasonably assert that some things are bigger than contracts. Freedom is bigger than a contract, so you cannot sign yourself into slavery. A free market is bigger than a contract, so if a company finds themselves in the fortunate position of attaining a monopoly or being a member of an oligopoly, they cannot make anti-competitive contracts that erect a priori barriers to entry for possible competitors. Because, you see, if there are artificial barriers to competition, we lose the free market, and descend into cartel capitalism which is the same thing as communism--except the people get less say.