Because the expansion is a completely different format for forum-based games, incomparable to Mafia.
Because in Mafia, you play to win, but in expansions, you just play; you can study these mechanics, or you don't have to, as you wish...
But then "blind Mafia" is also not Mafia, but some kind of "simplified expansion" in which you "just play," and whether you win or not depends on how His Majesty Random decides...
So, either you successfully hang a Mafia member based on deduction, or you lose your own teammate...
Если где-то чего-то убудет, то в другом месте добавится.
(Закон сохранения).