What functionality is missing? What is unsatisfying with the current situation?

Currently, only one version of each article exists. It is not possible, for example, to call up an article of its older version, or to make a single backup per article.  

How does this feature request address the current situation?

In many programmes there is something like a backup function that saves the last versions of a file. For example: a version from ten minutes ago, one hour ago, yesterday, the day before yesterday, one week ago, one month ago, etc. (Only if the article is currently being worked on).
Maybe the whole thing could be made configurable. Or manually versions with a „Backup now“ above or beneath the „Save“ button, where you can decide which backup-slot is saved. Or a FIFO (first in first out) backup system per article. Maybe with 5, 10, … (Journeymann/Grandmaster/…–Tier?) slots.
Duplicating an article would also be nice, but that’s probably a different topic.

(I don’t know to what extent storage costs would be a problem, but I personally would be fully okay with additional costs on my side.)  

What are other uses for this feature request?

Reduce the risk of cardiac infarction if you accidentally delete passages of an article and you are not aware of it until the next day.