[debatem1]

It's communication. If you communicate what you want and not what you don't, it's successful by definition.

The point made above is that sarcasm can be a way of communicating what you want (eg, "you're late") without what you don't want ("you should be ashamed/feel bad/apologize/etc"). This unwanted implicit communication is common in blunt statements of fact and is part of why that communication style is often described using words like blunt or harsh.

In this sense, sarcasm and similar serve the opposite role to the one you describe: a way of jokingly or obliquely raising criticism without demanding a direct response. Of course, those criticisms can be personal-- but that's a property of criticism, not of its style of delivery.