Consider the perspective of an ordinary wallet user whose sole concern is the availability of code for scrutiny and verification.
An ordinary wallet user does not have the requisite knowledge or ability to review the code themselves, and thus they rely on the community doing it for them and publicly flagging up any bugs,
Do you think that ordinary wallet user like, let's say n0nce, requires outside help to review the code himself?
Do you think that he will not flag bags (if any) in the code and be silent on his finding?
You don’t need a lot of skilled wallet users, just a few to make the presence of any bugs available to community.