No they don't, there are laws against that, for example you can't decide to ostracize black people from your company, you will get sued for that.
So its fine to fire all black people to ostracize them? No, of course not, so no you are wrong here, there are more limitations than that, people have rights protecting them from a lot of ostracism.
This works because people can choose to not be jerks, but they can't choose to not be black.
What if they could? People can change gender identity nowadays, and it's not outside the realm of possibility that people could change their phenotypical characteristics (transracialism is a hotly debated topic).
I'm sympathetic to the argument that the dynamics of the Internet have made some tools more or less suitable for purpose as what they used to be, but the idea that we can just assert "no ostracization" is flatly insane and totally antithetical to the marketplace of ideas.
Heck, downvotes here in HN are basically the same thing. If a statement doesn't comply with both the explicit rules and implicit assumptions and culture here, it will be downvoted to oblivion. And it is one of the major mechanisms that HN uses to ensure this site remains useful and relevant even with the large number of participants.
If you're in a car that's going way too fast, do you tell the driver not to touch the brakes because it "leads to us never reaching our destination?"
Anyway, we're currently seeing the reign of the "cancel culture is the big problem" crybabies. Turns out they just thought the state should have the power to decide who's allowed to have an opinion.