| One form of grease to keep the wheels of capitalism from jamming up.
Competition yields innovation. However, it's not always the best way to make a profit, which is what capitalism is about. A company that has no competition can make more money, and has less pressure.
These laws and regulations are there to make sure that a company does not get into a position of dominance where they can eliminate and prevent competition, whether it be due to mergers, buyouts, or just plain manipulation of the market.
Lack of such laws leaves the potential for eventual domination of the economy by a few giant corporations - or even one. | 
