Political power. Economic Power. Personal Power.
Transnational, trans-generational money is the biggest power on the planet right now. Within that, there are factions, rivalries and competitions, but like a bacteria colony, collective decisions happen which benefit the colony and completely disregard everyone else.
If you want a real, effective, democratic capitalist society, that benefits the largest amount of people, you put limits on power at the top, which means limits on the amount of money any one person, or organization is allowed to possess, or control.
The founding fathers assumed that government was corruptible, and put in checks and balances. This didn't go far enough. Everybody is corruptible. Everybody. That includes businesses and individuals. The damage they can do can be limited by checks and balances. In the case of individuals and organization, it can be limited by putting an upper bound on the wealth of individuals via taxation and the size and scope of commercial organizations. Antitrust laws were an excellent first step - if only they were enforced, which they would be, had the legislature and individuals responsible for regulation not been purchased by the wealthy.