The reversed question mark is actually to announce a question so when you speak the written sentence you know in advance what tonality to use. So if you read a reversed exclamation mark or a reversed question mark you will know right before saying that written sentence that it is either a question or an exclamation. Reversed exclamation and question marks are rarely used though and it is something only used in official letters or books. Not even publicity for the most part.
WE AIN'T DEAD