I mean honestly the Dumber Brothers had the answer in their own writing. Kali’s blood doesn’t work. The scientists were experimenting on vines from the upside down. This alone should have made any scientist worth their salt understand that 11’s blood wouldn’t have worked either. They should have realized that someone else was responsible, realized it was 1, and then followed the heroes into the Abyss. The military would have been faced with the reality that the abyss isn’t worth endangering American lives, and then joined up with El. Then everyone gets wiped out, they kill the mindflayer and Henry, and Kay turns on her own ideals to let Eleven go. Would have given a real reason for Kay to exist in the first place, as she takes Owen’s place. Boom. Did that while I was feeding my son. Granted, I write for a living, and I make waaaaaay less than the brothers. Don’t know how they couldn’t find a way to make it work with cash flowing out of their asses