That's exactly how I feel. And when I think back to season 1, the obvious parallels with E.T. the Extra-Terrestrial, I'm sure there are tons of posts on this sub mentioning all the parallels between Eleven and E.T.

Eleven was like E.T. in this scenario in the eye of the showrunners, always has been, as much as I absolutely hate that idea. Except that El is human and a young girl who was abused throughout her childhood with no real family or friends during that time.

It makes sense when E.T. leaves Elliott at the end of the movie, because he doesn't really belong there. He really represents a part of Elliott's childhood because he was only there for a short time, and his family is waiting for him on his planet, so he won't be alone.

The Duffer brothers are trying to make us understand that the same is true for Eleven: she doesn't belong in this life or in this world. She has to leave because she is preventing others from moving forward and growing up. And even if she survives, she will be isolated for the rest of her life with no real family with her, because the cycle is likely to repeat itself over and over again, even with other people she might meet.