Interesting take. I think there is a highlighted problem of the only reason Ellie ever got mad at Joel in the first place is because Joel is an idiot.
The only reason she gets mad at him is because he doesn't tell her the full story, and him hiding information makes no sense.
In reality, the fireflies had no idea they could make a cure or give everyone else in the world immunity to the fungus. All they knew was that Ellie's brain had a strange chemestry that made her immune. In order to even begin to experiment on developing a cure or vaccine or something, Ellie would have to die. And potentially there would be nothing that could be done. Ellie would have died, and that doctor could not have been able to do anything with it. Or since the world is dangerous as fuck, that doctor could have easily died three days later from some random infected, or a scars attack.
A vaccine, a cure, all of that could have taken years, and there was no reasonable plausibility to it saving anyone except the settlement that the doctor lived in. Remember everything is fucked, how do you continue to synthesize a vaccine? You can't.
If I were Joel, in the moment where Ellie demands the truth, I would have said this:
"Ellie, the....immunity you have....it's in your brain somewhere. They said....they needed to do tests on you. On your brain. These tests were no guarantee a cure or even treatment would work. But in order to do these tests......they'd have to kill you. I couldn't let them just kill you for nothing. I wouldn't let them. They tried to stop me.....but I got you out of there...to live. The world can't be just fixed, not anymore, maybe not ever. So I lied, and I'm sorry."
While not perfect off the top of my head, it gives Ellie more of his motivation, more of his reasoning. Rather than what he actually tells her.
I guess the biggest thing is that you are right. The game has no point because it has too many plot holes and logical blank spots that prevent it from having a point. Anywhere you look at it and think about it, none of it makes sense.
People have been saying that Joel's death was fine because Joel was evil in the first place and that's partly true. But he became a beloved character dispite that. and that way he was killed was extremely poorly written. Kill Joel, that's fine. Even make the story about Ellie's revenge, that's also fine. But it has to be believable revenge.
Instead it feels half-assed and I never got the feeling that the characters ever truly wanted vengence.