yeah any doubts i had about dark!dany were erased with this episode. they used olenna to (1) give dany permission to disregard any good counsel from her advisors and do what she wants, and (b) give dany that pivotal, all-important speech from adwd about embracing the dragon. they couldn't show dany conversing with blades of grass, so they had olenna serve that purpose, and there's no way they included it just for shits and giggles.
You took Meereen, [Olenna] told her, yet still you lingered. “To be a queen.”
You are a queen, her [Tyrell rose] said. In Westeros. “It is such a long way,” she complained. “I was tired, [Olenna]. I was weary of war. I wanted to rest, to laugh, to plant trees and see them grow. I am only a young girl.”
No. You are the blood of the dragon. The whispering was growing fainter, as if [Olenna] were falling farther behind. Dragons plant no trees. Remember that. Remember who you are, what you were made to be. Remember your words.
“Fire and Blood,” Daenerys told the swaying grass.