In what application is it like this? I don’t find this true at all. It’s a completely customizable sidebar.

Office has a particularly annoying dark pattern when saving a file. It hides the regular save dialog behind a tiny button in a confusing UI embedded in the main window that is designed to misdirect the user into saving files on OneDrive.

Many other programs do still open the standard file dialog directly, but even there, the local drive amd directory hierarchy is hidden behind a folded "This Computer" node in the tree view that is itself below the fold most of the time.