wikipedia.org wrote:

In case it's not obvious, this proposed feature has an Achilles' heel...
cl_timestamp can be reset by accident or vandalism (by removing and then
re-adding the category), and there's currently no way to undo the change, making
it unlike almost every other feature on the wiki. While it's be possible to add
the ability to undo a cl_timestamp reset, it would take a fair bit of extra work
and probably require a schema change.

If the "undo" bit isn't implemented, the feature is probably unsuitable for
deletion processes that have a fixed schedule, and where there's more potential
for misuse. But it may still be useful for other maintenance categories where
the schedule isn't quite as important as it is for deletion processes. On
enwiki, these tend to be the categories that don't have date-bots working on
them anyway. (though even there, templates that put their transcluded articles
into categories make it easy to reset a large number of cl_timestamps at once,
and the only way to prevent this is to fully protect those templates, which
again limits this feature's useful scope, since at least on Wikipedia, editors
prefer to not fully protect templates)

• This bug has been marked as a duplicate of bug 1289 ***