DoomSooth: Even if they don't let us have access to all older versions of a game, they should let us download offline installers of any version we can roll back to. You know they still have the installers. How else would we be able to roll back?
They have some sort of
SVN archive.
The download works the same way for every version, no matter if it's the newest or the oldest one available.
It works basically this way:
Upload #0 Upload of the original version, files contained are A, B and C
Upload #1 a patch is applied, file B was changed, let's call it B1 from now one (even if the file keeps it's original name)
Upload #2 another patch is applied, D was added C was deleted
If you download and install #2, you get the files A, B1, D
If you 'roll back' (or download and install) #1, you get the files A, B1, C
If you 'roll back' (or download and install) #0, you get the files A, B, C
In addition of course they run some script that would set some registry settings or install runtimes.
No offline installer whatsoever is needed. If it was, Steam, Epic, Origin, Uplay, Microsoft XBox store and Rockstar would have a serious problem.
A installer is not some magic tool that brings the game to your hard disk. It's just a image of one of these uploads with the logic to unpack the files to your target directory.
If at one point they wanted to remove all previous versions, they would move the old files from #1 and #0 into #2 (if needed, the original B and C would not be included), removing the old restoration points.