Online, among adults, yes. An "attack" online is just words. I expect adults to be able to survive that.
By talking about "surviving", you're taking the argument to the extreme. You don't really believe that an appropriate reaction to witnessing any non-lethal attack is to stand around with your hands in your pockets, do you? Even if we're confining matters to verbal attacks, I think there are some points you're missing. If (for example) someone uses a racial epithet in speaking to someone else, do you really feel that it's inappropriate for anyone else to say, "Hey, that ain't right"? Because that's the kind of thing we're talking about here.