Well if this happen, the earth main is/was a traitor or a spy working for/ spying Orochimaru since only through him you can get curse mark. What I want to know is why Naruto doesn't have blood limit if his mother have it.

Yeah well at the time Anko has the mark from Orochimaru, Orochimaru didn't betray Konoha yet. The main lives in the same time as Naruto, so only if he is a traitor or a spy can he get the curse mark. It might be fun to talk about this but it's useless since earth main will never get this tag in the game.