Put differently: if there's no reason to lie, does the lie still count?
ADvance does introduce a tracking issue: I buy it, claim not to have action cards in my hand, you can't verify it. You could (and as I understand, are) arguing that it doesn't matter since it's impossible for me to gain anything out of that (pun not intended), and I probably agree, but it's not obvious that everyone would.
PPEd