This is like reporting a spam (Similar). Modules/Themes can be reported by users that are being duplicated or useless etc... This is one way to reduce the duplicates and Useless modules from Drupal.org search results/Database. And I recommend that the page should also show how many users have reported and Why?.
Reported Modules/Themes can be checked by the community members and they will choose the actions that need to be taken as needed.
I have downloaded more then 200 modules.
In Search Results, I have found that there are many many modules that have not been maintained for a years. If such module is useless and appears in search results that means we do need reporting on drupal.org
At least such modules should not appear in search results if they are useless and can cause the entire site to crash or even just case problems.