Sarcasm is by definition intended to mock the recipient, so in that respect, that's not the level of discourse we strive for. More typically sarcasm refers to saying something but implying the exact opposite, which is obviously not what's happening here, and happens all the time (we've even adopted the text in blue convention for better conveying what is typically a tone of voice).
There is nothing gained in mocking a legitimate point of view by saying that the person is living in fantasyland. If someone posts on how we're going to trade for Shohei and win the World Series? Sure, they're probably living in fantasy land. That's not this.
This forum has existed for decades on the premise of a different level of discussion than the typical "win the internet at all costs" type posting that ends up in a race to the bottom.