No one should have to walk out of a three-hour concluding chapter trying to work out how and why things happened the way they did.
I think it’s perfectly fine to leave the audience with questions. Not everything has to be perfectly and completely explained, especially if the film maker expects the audience to be smart enough to connect the dots, or if they are purposefully holding something back. Sometimes part of the fun is working through things for yourself. And in a narrative that, 22 movies in, has been clearly established as ongoing, leaving unanswered questions is not necessarily a sign of bad film making. The MCU is a sort of weird multi-billion-dollar hybrid movie TV show … thing. If you break the films down into “seasons” based on their “phase”, then Endgame is the end of “season 3”. Even season finales leave some things unexplored to give the next season some threads to pick back up.
In particular, if the Russos do actually have answers to the question of what went on with Cap during his reverse fetch quest (or at least, if they’re willing to let on that they do), then I’m willing to accept that in Endgame, we got the beginning and end of a thread that could well be explored in the future, and I’m content with puzzling out what that thread could possibly be until we get an official answer. Again, that’s part of the fun.
