you can be satisfied with those explanations, and that's fine. you are in the minority though. i can't let a show slide, who has had excellent writing and story and character development for many seasons just phone it in like they did.IMO there's a lot there that's easy to explain if you ask me. Arya stopped in the courtyard and didn't follow through because the Hound talked to her and finally made her realize that her desire for revenge was turning her into the same person that Hound was, someone driven by hate and fated to die and Cersei was going to die anyway no matter what Arya did. She finally realized that. The mountain and the Hound always hated each other, thats why the mountain shoved the hounds face in a fire when they were kids. Even though the mountain had become mostly "undead" himself, the hate for his brother was still strong so that explain not staying with Cersei for me. The hound let Cersei walk by because of what he told Arya in the courtyard, remember he told her that there was no reason for Arya to keep going to kill Cersei herself because she was going to die in the fire/rubble anyway. So he knew she was dead no matter what.
It's just one of those things where you can find fault in anything if you look for it, just depends on your view is all. Almost any Tv show/movie can be faulted under scrutiny. For me I think there's answers enough for my taste, and I enjoyed the final season and don't feel it was rushed or bad in any way. It's just a Tv show, it did its job and keep me entertained and wanting more but I was pleased with the way they ended it.
you may not fault the writers but i do. they didn't have to make the last 2 seasons short, they chose to thinking they can wrap it up and they were wrong. now they're saying things like, if you didn't know dany was gonna turn into the mad queen, you weren't paying attention. no dude, don't blame us for where you failed. even the actors themselves wanted things done differently. they're either too nice, don't wanna burn any bridges, have a sense of loyalty or for whatever reason, can't and won't really say what they feel. i choose all the above
if hound was gonna stop arya, he could've and should've done it at winterfell. if mountain was gonna say screw my queen, he would've done it when him and his brother saw each other during the meeting to call a temporary truce. also how would hound know that they were doomed if they walk in? you can't just serve your audience excellent 5 star dining and in the end sling buckets of baby food at us and expect us to be ok with it. you not only fail with the content but the delivery as well. and then say, well, you can't please everyone, you're whining because you didn't get served what you were expecting, in the way you were expecting it.......
again, i don't mind the results, i dislike the pace and delivery.