YY, I know that, and I'm not disagreeing.
But if you are quoting something (eg., 'not acceptable' from the rule book), it's not wrong to use them and it looks a little clunky to use both, sometimes.
I don't understand why you think they're for implying sarcasm. They're not. They're just for quoting. It often looks sarcastic because you're pointing out the distance between yourself and the originator of the phrase, but that's interpretation, not the primary meaning.
Oh, lord. I have become a punctuation pedant.
There is no hope. 