What were your conversion rates like through other sources?
Though I do agree with you that buying likes is useless and a waste of money.
However, it would be willful blindness to ignore what I can verify vis-a-vis the FB paid promotion. Moreover, when I can verify the majority of likes are from illegitimate users/profiles, based on not having any posts and otherwise being inactive, then I have no expectation the users clicking the ads are any more legit than users clicking the promotion. If FB had faith this was not the case I see no reason they would not disclose the users who clicked the ads so advertisers could confirm their legitimacy.
As for the second part probably because it's a huge privacy violation.