In ranking, there's "query independent" and "query dependent" quality signals.
Query dependent: "for this specific query in the past, how likely are people to click this result?"
Query independent: "what is the PageRank of this document in general?"
The query independent component is normally the more important ranking factor.
The query dependent signal is more often a "twiddle" on top.
If this weren't true, then at the very beginning Google wouldn't have been able to get so far so quickly with PageRank as the main innovation.
This means that systems where most people can agree on a baseline quality can have good ranking even if there's not much overlap in queries.
One user's completionist approach to checking every suggestion could improve query independent signals for everyone.
You only need a very small number of highly motivated users to improve query independent signals for everyone.