With increasing hosting of images on commons, there arise vandalism concerns.
Images hosted on commons cannot be protected by admins from en.wikipedia. There are only about 25 admins on commons who are also active on en.wikipedia. The commons community has turned down several requests for adminship from en.wikipedia admins in good standing who wished to become admins at commons in order to deal with vandalism on commons that affected en. It is commons policy that significant involvement in commons in particular is a requirement for adminship, regardless of involvement in other projects.
Another problem area is that images on en: supercede those on commons with the same title. Therefore, an image protected on commons could be vandalised by uploading a vandalised image by the same name on en (Unless there is a technical solution to this that I am not aware of. I haven't tried it). Though cumbersome, an en admin could conceivably use this as a workaround for protecting images that have been vandalized on commons.
In general, I believe that there should be more trust and cooperation between the projects, to the point of having some process for fairly routine granting of commons adminship to en admins. This might be a situation where partial permissions -- protecting and unprotecting pages only but not blocking or deleting -- might make sense. A similar process should be in place for the other large wikipedias, such as de and fr.
I do note that there is an agreement to protect main page images that are on commons. My concern is with other prominent pages. The unexpected vandalism spree that accompanied the last U.S. presidential elections would be an example.
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