Consider if one makes any edit to a Rule, DE, Extension, etc, but then undoes/removes the edit, they are still required to build a library and move it forward to Production with a "changeless" change.
Request is for a mechanism to "revert to the last built state". In other words, "trash any modifications to the element that do not match at least Dev state". e.g. If I have a library built in Dev, I should not be able to "undo" the element as it is locked in the upstream, but if there is no Dev/Stage/etc build, and the current state of the element === the current published state, and there is no delta to send upstream, I shouldn't have to build and publish a new (empty) library to flush it out of the backlog.
Replicate at the most basic level:
Choose a currently published rule and edit the rule by renaming it (append an "!" to the end, for example)
Edit the rule again and remove the "!", returning it to essentially it's previously unchanged state (i.e. it mirrors what Production shows)
Notice if you attempt to "Add All Changed Resources" in any future Development build, this "change" will show up, and the only way to resolve it is to publish what amounts to be the same library that exists in Production already.
Granted, my example is frivolous, but the case in point is making edits to be tested in Dev that may not ever be moved to Production will necessitate a full "publish flow" regardless of delta existing.