Also the line can be blurry with celebrities since they will engage in business deals.
I think it's unacceptable to send the mob after an individual to destroy their life. I think there is more wiggle room when the target is a celebrity who signed up to be a public figure. Same with politicians. Not that it should completely unlimited, mind you, but if someone chooses to be a public figure then they are accepting that some people will be critical of them.
With companies, I don't know if there should be much, if any limit to what gets said. Companies are not people, Mitt Romney's opinion notwithstanding. To me it becomes a moral wrong when there is a human target.
What seems to have changed, from my perspective, is that liberalism has stopped being the values system championed by the left, and instead what we have are two different visions that are both more or less authoritarian.