Honestly explicit sarcasm indication should just die out entirely. Might as well be writing it longhand as "Just in case you missed it, this is a joke haha." every time you tell a joke.
I’m assuming you’re joking, but maybe that’s exactly why we need explicit sarcasm demarcation.
I might even offer a corollary to that law, which is that the more unclear a statement is, the more inscrutable a it's intent, the more likely the original author will insist that it was 'obvious' sarcasm.
There is nothing to refute in it, but, just to prove it wrong: sarcasm is commonly denoted in spoken English by intonation.
I don't like your replies, so I stop this conversation with you.