For one, pro-business does mean pro-free market. In some cases, to promote competition the government has to step in. If a corporation can earn more than an economic profit, it will. At least, assuming profit is its sole motive.
For two, there are genuine market failures that more free market cannot solve. Externalities, missing markets (e.g. the market for clean air), pervasive uncertainty, and free riders are just a few problems the market is unable to overcome without assistance. Do you, for instance, imagine that an individual consumer is going to be able to afford even a part of a missile shield? National defense is one example of a very important service that the free market does not seem able to provide on its own. Private fire services were one reason that the Chicago fire was so bad; houses without coverage were ignored and then presented a hazard to the rest of the city. By the time all the fire services were mobilized, it was too late.
Even should a freer market provide an overall pattern of economic growth, looking at averages can be misleading. Medians are more typically a better indicator of how most people are doing. Do you think, for instance, that the common good (i.e. total utility) is really served if ten people earning $20,000 a year have their salaries slashed in half while one person earning $110,000 has their salary doubled? There may be an overall growth of $20,000, but it would dubious at best to claim that people are overall happier for it.