I'm no chess expert, but I think because at 17... Bxa4 followed by 18... Bxh2, the double bishop sacrifice, it's not obvious how Black will then dominate the re

I'm no chess expert, but I think because at 17... Bxa4 followed by 18... Bxh2, the double bishop sacrifice, it's not obvious how Black will then dominate the rest of the game.