Part of the problem here is that you're abstracting the actions of a handful of relatively powerless people to a principle: "People whose opinion I don't like can be banned from society." The 'I' here is, from your framing, the 'left' or something.
Strawman. The fired people you're talking about weren't banned from society by the people pointing them out on the internet. If someone's on an international flight yelling racial slurs and causing a commotion, and someone else publishes video of that person yelling racial slurs on an international flight, it's not the people commenting on the video who fired that person from their job. It's their employers. What would be the alternative? No one takes video of the person yelling racial slurs? Or, if the video is posted, no one comments on it? Or, maybe, the person yelling racial slurs could simply avoid losing their employment by not yelling racial slurs on a flight full of people with their phones out? Or maybe the employer could choose to ignore the negative publicity and keep the person on staff despite the risk to their revenue? Who exactly is the responsible party here?
I generally find it pointless to point out that 'right' perspectives suffer from a lack of practical logic--pointing out the fundamental irrationality of a position rarely changes the mind of the person holding that position. But, your position ignores power differential between people--your argument is a matter of 'principle,' but this isn't fundamentally about principles.
Is your argument then that a person yelling racial slurs on a full airplane shouldn't have their employment threatened by their behavior? That their employer shouldn't fire them?