There are a lot of more people discovering the game than people who already played it, hence we cannot add the skip all feature for everything since it would ruin the game experience for new players.
But this demo will be compatible with the final game, so if there is an update, as long you keep your saves folder, you wouldn't have to go thought the whole prologue! (And if, in case you unfortunately loose your save folder, if you don't delete your persistant variables located in the hidden appdata folder, you should be able to skip already read text even without the skip all function)