Ensuring high quality sources where needed, especially science/academic topics (narrow focus)
Fragment of a discussion from Talk:Task force/Wikipedia Quality
A such search engine will help especially for fact checking.
Downside is editors putting putting pieces of "opinion" from various RS without thinking the weight issue.
During a peer review an editor asked why XYZ reviews should be mentioned and given weight. Someone answered by saying that those reviews came RS websites figuring in the anime/manga project list of RS. Using list of RS is great but understanding why those sources ended in the list is even better.
About 90% of articles without sources, we should do something to make people understand that it isn't an acceptable norm. Once during an Afd i found an editor arguing that a not sourced article isn't a big deal and like many others ones. I wanted to slap him.