Er... This is 💯 your self insertion into the text, though...🙄
By peaceful city you mean... terrorist attacks by the Harpy's Sons, besieged by the Yunkai coalition and Astapor plague victims at her gates?
I thought you were talking about the books?
In the show, Dany is nonsensically threatening to burn down Quaithe when in the books she was welcomed into the city after asking nicely. Xaro and Doreah weren't killed by Dany - Doreah died in the Red Waste and Xaro is still alive, a frenemy of sorts to her. In fact almost all her original khalasar (inner circle) are alive in the books, and helping her rule. orah in the books is a potbellied lecher old enough to be her grandfather, not the noble Knight that looks like Iain Glen.
She didn't even want to banish Jorah in the books and certainly didn't need Tyrion's advice not to kill him. It was Jorah's own arrogance and refusal to apologise ---- for selling her secrets to kill her! - that forces her to turn him away. And it goes without saying that in the books, Tyrion is Team fAegon and has never met Dany. Since Barristan Selmy is not dead, she has a robust inner council and events in Mereen are already underway, if they ever meet, Tyrion is not going to have the same arc and become her Hand. The show takes all her intelligence and strategy and cunning and gives it to Jorah, then Tyrion.
The show has Dany feeding people to her dragons (and killed of Barristan Selmy to justify this, something that both the actor and GRRM have talked about). Dany constantly needs to be talked down from violence. In the books, Dany's ineffective against the terrorists because she is not violent enough! Even though she's adopted the Westeros practice of taking cupbearers, she can't bring herself to harm any of them. (Compare to Ned Stark who would have killed Theon Greyjoy at Robert's command. He won't have liked doing it, but he would have done it all the same).
In the books, it's Quentin who (accidentally) releases the caged dragons. Dany didn't free them to go on a rampage.
Dany's not failing at Mereen because she's too violent, but because she's not violent enough. "Fire and blood" isn't her giving into madness, it's her reconciling to the fact that - like every ruler in this world - she can't rule without some degree of ruthlessness. That her compassion needs to be stifled to an extent for her to be effective.
Like the idea that the show whitewashes Dany is so far from the truth that it's borderline ridiculous that people assert this.