That's not the populist notion on corporations at all. The populist notion is that corporations' incentive structure, set by their board/leadership, causes them to act at the expense of rank and file workers and consumers.
That's very different than "evil" or "stupid".
They are models, specifically sanctioned by law, that are organized around particular sets of interests.
Just because there are subsets of people whose self-interest is aligned with particular corporations' doesn't mean that those interests are aligned with the self interest of everyone, or even a majority of people.
And this isn't to say that there isn't an important role for corporations to play in the world, but to suggest that their form and function is the result of everyone acting in their self interest is oversimplifying things dramatically.