Strongholds with no active clan members
Numbers of strongholds are built and subsequently the clan dies out. Few, if any, of the chiefs hit the "destroy the stronghold" button when they quit so there the SHs sit, burdening their kingdom with dead influence and sometimes exercising dead control over Pioneer tiles or otherwise getting in the way.
So my suggestion is that the developers introduce some programming to clear away any stronghold where there has been no active clan member for six months.
Unlike clearing away dead towns, clearing away dead SHs does not involve making any change to anyone's account.