A Benghazi cover-up makes no sense, and could not have had any conceivable goal.

"...the reason it is absurd to suspect the existence of a "cover-up" over the Benghazi attack is that such a cover-up could not have had any conceivable goal. Back to the beginning: the underlying accusation about Benghazi is that the Obama administration deliberately mischaracterised the terrorist attack there as having grown out of a spontaneous demonstration because that would be less politically damaging. Such a cover-up would have made no sense because the attack would not have been less politically damaging had it grown out of a spontaneous demonstration. The attack on the Benghazi compound would not have been any less politically difficult for the administration if it had grown out of a riot, nor would any normal voter have expected it to be less politically damaging, nor would any normal campaign strategist have expected any normal voter to have expected it to be less politically damaging."

Benghazi-gate gets even more ludicrous (Economist)