They this kind of allude to this, but they were so busy ensuring that people like the ending, which means people like the winners at the end i.e Tyrion & Starks that this ended up getting lost in the happy ending of good heroes killing bad Dany.

Tyrion right from season 7 has been making such plans that they protect Cersei. He suggests capturing Casterly Rock which doesn't harm Cersei & Jaime. Before DragonPit meeting, he tells Jaime that he hopes to keep Cersei alive. After Missandei's capture, he once again hopes Cersei will surrender peacefully. He frees Jaime to help Cersei escape. And finally he shucks the Handpin & goes all out to convince Jon to kill Dany, only after bawling over the dead bodies of Cersei & Jaime.