Resistance against antibiotics cannot come free for bacteria. If we stop using some, the resistance should vanish as quickly as it turned up, shouldn't it?
As such, once the antibiotics are stopped, non-resistant bacteria may be better able to compete for resources and multiply.
There's a reason super resistant strains are most commonly found in hospital and health care settings: https://www.cdc.gov/drugresistance/biggest-threats.html
If the ongoing cost of the mutation was truly free, one would expect it to spread out beyond these places more prominently.
Edit: I may have under-emphasized that there is no guarantee, and we shouldn't rely on this property.