Unfortunately, this is not true. If the listing in the Binder is present, but the file appears empty, the most likely reason is that the .RTF file containing the actual content is missing. If – as often happens – the file is present on a cloud server, it can be recovered by convincing the cloud server to download it to the local system. (And the Support team can certainly help figure out how to do that.) But we usually won’t be able to recover anything useful from the project as it exists on the local system.
(With Scrivener 1 projects, it was possible for content inside the project to get “detached” from the Binder index. But that behavior had slightly different symptoms and is largely prevented by the Scrivener 3 project format.)