Viral ostracism is quite different from the local-scale shunning of the past. Having a torrent of people shunning you for someone disagreeing with you is unjust.
"Having a torrent of people shunning you for someone disagreeing with you" is the same reductionist self-pity that people have used for ages to defend themselves from ostracism, which may be just or unjust, more subjectively or less subjectively. Sure, the internet amplified it, like everything else with a social component, but I think you're wrong to imply they are qualitatively different.
If scale doesn't matter, then there is no difference between individual officers observing a person of interest and a city-wide network of traffic cameras observing that person.
Hopefully you can now see why your objection is weak.
Well too bad, it's totally legal, normal, and part of human society. Now if you want to talk about the effects like blackballing/listing and other things that ought to be banned then I'm all ears. But if you're going to start forcing association between private individuals and private groups then you're gonna have to show me case law that says people gotta associate with each other. It's like saying that folks gotta associate with racists in their families just cause.
Also, I'm all ears on abolishing at-will (so-called right to work) employment laws. If you abolish the laws that make social ostracism through social media so bad then it don't really do much. Plus, I've yet to see a celebrity that's been 'cancelled' actually physically or psychologically suffer. The worse I've seen is Alan Dershowitz not being invited to some old friend's dinner parties in Martha's Vineyard (how horrible! /s).
