Two properties that significantly increase the value that an individual business can provide to users are economies of scale and network effects. The former lets them provide more user value for less cost. The latter gives users N^2 increasing value at only N cost.
But those two properties are also fundamentally anti-competitive. The fewer independent competing businesses there are, the greater these properties are maximized.
This doesn't mean capitalism should be completely discarded, but it means there is an unhealthy positive feedback loop where the system will trend towards consolidation and monopolies unless some other equally powerful force balances it out.
At the same time, going too far in the opposite direction and having many competing small companies may also be worse for consumers. You get more optimal pricing of more inefficiently produced goods because of the lower economies of scale and network effects.