I get that irony is a sometimes-misunderstood concept. But I thought we all pretty much got sarcasm.
“Russia, if you’re listening, I hope you can find the 33,000 emails that are missing” wasn’t sarcastic. Maybe he was kidding. Maybe he was being snarky. But it clearly wasn’t sarcastic.
“Obama founded ISIS” wasn’t sarcasm. Exaggeration? Sure. But it clearly wasn’t intended to be understood as sarcasm.