This has been discussed before countless times on Meta Stack Exchange:
Why isn't providing feedback mandatory on downvotes, and why are ideas suggesting such negatively received?
Encouraging people to explain downvotes
Such a policy would not be enforceable and it doesn't solve the problem.
No. ♦ moderators used to be appointed by Stack Exchange staff, chosen from subject matter experts and users already familiar with moderation tasks on other Stack Exchange sites. Nowadays, they often hold elections, just like on main sites. See this recent example.