It's not that they can't read, it's that you didn't put enough info in there to distinguish it from the genuine article.
If, for example, I were to satirise an antivaxxer over text (like here!) without being able to use any giveaway symbols like /s or alternate casing, I would have to go for the most batshit insane example, to the point where its not funny, just stupid. Something like 'I got vaccinated and turned into a fucking velociraptor. Jurassic Park is real! Don't believe the lies!'
Fair enough if that's your humour, but if I try to go for anything more subtle than this, I can easily be mistaken for a genuine antivaxxer, because it's not far off the BS they actually spew. In real life I can put on an exaggerated Karen voice with exaggerated resting-bitch-face and people will know I'm playing a character, rather than espousing my genuine beliefs. I can't do that over text though, so what's the alternative?