Having seen it, I do think sobbing's a bit of an overreaction to Endgame, but why shouldn't people be emotionally engaged by fiction? Isn't that the whole point of fiction?
Sure, the latest superhero film may not objectively be the best fiction to be engaged with, but remember this is the 22nd(?) official Marvel film, so that's 21 possible times for that connection to be made, and for people to care. That emotional connection is the realest thing there is to our minds.