Suddenly we were receiving more submissions than can be handled. Its starting to pile up and slowing everything down. We created more tools and made site smarter to ease approving, but its easier and faster to submit links than it is to check/create/approve links, so we temporary disabled link submission for everyone, except for few.
Higher-up told that they can't accept random people to moderator positions. Because you can't really tell if person want to become moderator to help out or become moderator so that he could accept own links first. Every now and then we receive messages where people ask to be moderators because they used to be moderator on some similar site. With current system, if you haven't worked us before you can't be accepted to moderators positions.
But more human power is needed to make approval system efficient. This why there is new system in development, what has been designed around linkers check and approve other linkers and users submissions. Linkers will get ability to check and approve others links, but when one starts to disapprove other links without valid reason, his right to approve links can be revoked by moderators.