I'd also say that the GP's statement isn't wholly true.
Inorganic growth is a different road to monopoly power. Vertical integration, another. As is abuse of existing monopoly power to gain a monopoly in a different market (see Internet Explorer).
The consumer isn't accountable for the actions of a monopoly. The main problem is that the monopoly becomes less accountable as a whole.
Yes there are issues with monopolies. This is why new laws must be created to protect against these monopolies.