Neil just doesn't know how to write good characters without manipulating the audience into how they should feel towards a character.
The audience is attempted to being manipulated into sympathizing with Abby through multiple methods, which I think are just extremely cliché and cheap writing techniques that usually fall flat. The biggest one, I think, is turning Ellie against Joel. Part 1 ends with Joel keeping the secret from Ellie that she didn't have a chance at saving humanity, raising the question of moral ambiguity of Joel's actions for the audience to mull over and discuss the right and wrongs of that. All well and good, a very good way to gain so much talk over a game.
The structure of Part 2 ruins this ambiguity by disassembling. Joel is killed by a revenge seeking Abby for his actions (how righteous!). After this event happens, Neil Druckmann, the masterful writer, conjures a feeling that he needs to cause a detachment from the audience against Joel (that evil, evil, man and this silly audience taking his side? The gall!). It is then we - the players, not characters - find out that Ellie has since returned to the hospital some 2 years ago and rummages through a random bag and \gasp** finds a tape. What is on this take you wonder? Why it is a conveniently placed confession on what really happened.
Revelations come rushing to Ellie and she has many questions that are unanswered. But get this, she finds that Joel has LIED to her. But lucky for the audience, we get to watch this unfold. We are seeing Ellie find out Joel has betrayed her, and lied to her. And at this moment, we find out - but bare in mind, this is after the fact of those horrific things Joel did - Ellie implies she would have indeed prefer to have given her sacrifice, because her life would have mattered.
You son of a bitch, Joel, all of my thoughts and mulling I did over your moral ambiguous actions to save this little girl, have now been changed by the hands of Neil Druckmann. I now know that in hindsight, Ellie would have wanted to give sacrifice, after Ellie has grieved and felt at fault and would always wonder "what if".
Anyway, my point is that Neil can't write. And this should have been revealed by Abby. A lot more could be explored. Hard to change your mind when you think about the silly techniques Neil uses