You are correct to say that it is believers responsibility to appoint elders and deacons. But the reason we do so is just like Moses; we can't do everything. The leaders of the Church realized that they could not take their valuable time "to wait on tables". Like Jethro's advice to Moses to appoint qualified men, the New Testament scriptures also lays down qualifications for those posts. We measure men and women against the scripture and appoint them accordingly. We ASSUME the men we appoint have been ordained from God based upon their past actions. If a person fails to live up to those qualifications, then they should be removed. But it is a big mistake to think that we have been granted some sort of mystical power to ordain people on earth. This is a very wrong Catholic notion.
God has not relinquish His sovereign control over us or "delegated His authority" for which we should be thankful for. He knows what is in our hearts.
True Harley, Ordination is only recognition of what God has been doing in a person’s life. Far be it from me to have communicated anything more than that. The reason for the qualifications in scripture are that the church might jude ministers and either accept or reject them.