Unrelated to WotC's adventures or 5e, I'm currently running "The Enemy Within" for the group featured in my Curse of Strahd and Rime of the Frostmaiden Post-Mortems. They have certainly been feeling railroaded and have openly complained to me that "nothing they do matters." At least the first part of "The Enemy Within" ("The Enemy in Shadows" is the first book) is probably the most railroaded campaign adventure I've seen - though Masks of Nyarlahotep is close.There is another point to remember. People get very, very bent out of shape about how AP's are railroading.
I've had players though, that are perfectly happy, I daresay happiest, when the DM is leading them by the nose. They are simply not interested in being the slightest bit proactive in how the campaign runs. The DM wheels up the plot wagon, spoon feeds the players, and then players then run through that.
So this begs the question, is it possible to have an epic, pre-planned adventure that isn't railroaded? You can have certain story beats, but when that story requires certain things to happen in a certain order, that's when it becomes a railroad.