Ross Duffer said Eleven's death, or disappearance, was integral to the story ending. Eleven represents childhood — and the finale is all about the kids of “Stranger Things” growing up.
Stranger Things has ended after 10 years, but the finale left one character's fate ambiguous, despite a definitive answer being more satisfying.
So instead, upon seeing that Ted is alive and well, one only has to assume that his grief was entirely focused on Eleven, ...