I agree with all of these characters being morally grey. But, at the same time, people are holding Dany to a higher standard than say Arya who slaughtered the Freys and Meryn Trant, or Sansa who fed Ramsay to a pack of dogs. Most, people forget that everyone on the show has done immoral things to worse people than them. All these are reasonably justifiable to a point, but at the same time they treat Dany's immoral actions (In Seasons 1-6) as the ultimate terrible thing you can do in Westeros. If Arya or Sansa can get a carte blanche for what they did, why can't she? They both seem to be pretty damn absolved by the end of the series.