Philip Welch wrote:
Featured articles should have guardians who fearlessly revert bad changes like this while taking useful contributions and massaging them into the featured whole. This would work a lot better than the salutory neglect system we employ now. I know this sounds ominously like WP:OWN, but it's needed.
This already unofficially happens, sometimes for better and sometimes for worse. Some articles are indeed neglected, but there are many on which you can't change so much as a bit of wording without attracting attention.
WikiProjects and setting up "related changes" watchlists are one way some people try to organize such oversight. It seems to work pretty well in some areas, and not even just for featured articles---if you add a new page to any subcategory of [[Category:Mathematics]], you're likely to get someone stopping by within the next few hours to fiddle with some part of it or another. (But then we have some very good and diligent mathematics editors.)
-Mark