I asked her what she had against the Greybeards and her response really reminded me of what the Sith say about the Jedi. She even tries to convert you to her side of the argument by lying: seriously! Talos founded he Empire because he listened to the Greybeards.
I don't think Delphine was lying it's just her opinion, if Tiber Septim had fully followed all the Greybeards teachings he would have been meditating at the Throat of the world instead of conquering himself a empire. The Greaybeards do teach pacifism which Tiber Septim defiantly didn't follow.
She is extremely angry and paranoid which is pretty Sith like though, but thats probably form being a spy and the Thalmor enacting order sixty six on the Blades.