The tag does two things. One, for people like me (ND ASD) the tag allows us to actually understand what you’re trying to say. Kind of a dick move to exclude people from the conversation. Two, and far more important, it’s no longer a question if you’re being sarcastic. That doesn’t sound important until you remember that 4chan literally brought back nazis because they thought ironic nazism was hilarious. And then all the closeted nazis used that to say “none of those people are being ironic, they all mean what they’re saying” to new, properly primed recruits.