I actually really liked that ending, and I was surprised so many people felt it was weak. I think it was very meaningful. I know some people complain that it "undoes" everything you do, but I think it makes sense as to why that's the most "correct" way of doing things. It kind of closes the circle across all 5 episodes for me, because I realized that the whole game was essentially Max trying to defy reality and refusing to accept Chloe's death. Then reality fights back. At every turn Chloe is fucked. If she doesn't die from Nathan, she'll die by train, or die by tornado, or die by Jefferson. Max then just goes all out and tries to change everything from the very "beginning" when her dad dies, and yep she dies in that reality too.
It's at Episode 5 where the hopelessness unravels. Episode 3's "photo time jump" was such a big leap, and in Ep 5 she had to make tons of them. She needed to constantly jump across realities just to "advance" an inch. Even the "best" timeline where she wins the contest, Jefferson gets arrested, and she's basking in the glory of everyone admiring her work, Max firmly believes the timeline is not fixed because the tornado still flattens the town and kills Chloe. Even in the best outcome the world is fucked. By the time you finally make it with Chloe out of harms way at the light house I realized this was just wrong. It wasn't satisfying. Yes, I saved Chloe, but the cost was enormous and the time leap abuse was just too much.
It's about that old adage about how the only winning move is not to play. It's not about the story of some intrepid hero who saves the world by changing little things about time, it's about the finality of letting go. She has all this power, and over the course of a week she's tested physically, mentally, and morally, and she goes through hell and high water to do what she genuinely believes right. But at the end of the day, fate and time and the "proper" order of the world is still there. After Max decides to let Nathan kill Chloe in the bathroom and after seeing how everything else unraveled, I thought "yeah, this actually was the best outcome all things considered". After the murder, Nathan rats out Jefferson, which means his plan and the "Dark Room" get discovered, the incident with Kate becomes obvious once they go over the photo binders so she gets the help she needs instead of getting bullied, etc. Things don't work out for a universally happy ending, but with the way all the plot threads concluded in that reality, I really felt like it was the most natural. It's not about Max just going back in time to that bathroom that she's just "undoing" what she did throughout the game, it's her having finally realized after everything that has happened that the original, most natural "timeline" was simply the objectively "correct" one. It just took her all that time to finally come to terms with that.