The part that makes a bad ShallowPage is when the thing being defined is already defined more satisfactorily elsewhere. Wikipedia:Wikipedia_is_not_a_dictionary article argues along similar lines.

If OnceAndOnlyOnce is important to you, then you need to encourage forces that counteract the tendency of people to document terms where they are used. The wiki will turn into a dictionary. ;)

The solution is to make linking to definitions easy. Use URL abbreviations to make it easy to link to Wikipedia, to link to Google 'define:' searches, etc.