It is different. Fundamentally different. One is retributive (A did it to B so B is “justified” in doing it to A, too) and the other is restorative (A took from B so “justice” is served by A returning it to B). Everyone is worse off in the first scenario (an eye for an eye and all...) while everyone is back to where they started in the second scenario.

A better example might be punishing a murderer with the death penalty. But most people who oppose retributive “justice”, myself included, do indeed have a problem with that system so it’s still not a particularly persuasive point.

If a person believes $action is wrong but are able to rationalize why it’s only wrong when others do it but it’s justified and permissible when they do it then it seems to me that the hullabaloo over $action is just a pretext and real issue they’re mad about is who is doing it rather than the $action itself.

You are missing the point of the retaliation, in this eye for an eye way.

The problem is that one side currently doesn't think it is wrong to do these attacks in the first place.

But maybe they will start to understand the harm, if they are subject to the same thing.

Yes, it is better for these cancel attacks to happen to nobody. But it simply isn't going to stop until people on all sides understand the harm that it causes, and likely the only way to do that is for them to suffer at least a bit of those same attacks.