Buying a competitor is always a dubious move towards monopoly. If the ideal free market is supposed to have all sorts of advantages, then anything which reduces the ideal-ness of the actual market must be viewed as negative.
Seems like I should have better explained why the logic doesn't hold. Even if we grant that an ideal market is a good thing (which is debatable), it's still not certain that all motion towards an ideal market is positive good. The space through which one moves may not be monotonically increasing in the goodness direction.
No, that logic doesn't hold. Further, I think you're conflating two meanings of the word ideal. In the context of an ideal free market, the meaning is closer to hypothetical and is pretty far away from the sense of ethical or practical goodness. Also, it's not clear that an "ideal" free market is a stable equilibrium. And lastly, if an ideal free market permits the existence of corporations (I'm not sure that it does) then it must allow one to purchase another.
