Thanks for your reference.I will gladly explain.
The secret sauce is the multitasking/multiwindow that iOS/iPadOS completely lacks. And, no, Stage Manager doesn’t cut it. My previous iPhone 12 Pro Max, iPhone 13 Pro, and iPad Pro 12.9 still cannot do all the things my Fold 4 can do. Please reference the post here for more detail.
The high cost will be a major factor, esp. if Apple makes a foldable device, as it usually is.
Also, the OS appears relatively better, since it's unlike Apple's iOS with its infamous walled garden, for file transfers, which is frustrating to many users who likes to move files off their iDevice back onto their computers. Not everyone uses/owns a Mac.