It may be true that "shame only works inasmuch as you believe folks have a point" (I'm unsure), but it's certainly not true that shame only works when the folks

It may be true that "shame only works inasmuch as you believe folks have a point" (I'm unsure), but it's certainly not true that shame only works when the folks doing the shaming have a point. People often feel shame when people criticize qualities that they do have that I think we'd both agree are not shameworthy. As well, some people have a tendency to, when they see criticism of a vaguely-specified group to which it is remotely plausible that they are included in, include themselves in the criticized group and feel shame as a result. These objections do not necessarily imply that we should not attempt to publicly shame shameworthy behavior, but such tactics do harm some people who are guiltless (unless "guilt" here is intended to include feeling a sense of guilt without having actually done something wrong, in which case the statement seems tautological) and guileless. So does asserting that they don't in a public setting like this, independently of whether the particular individual the assertion is deployed against is themselves worthy of disapproval.