Where did the concept of celibacy come from?
God. I mean if it is done right. It is not automatically good.
would you say that it is preferable to have a celibate church leader?
Paul gives standards for who qualifies to "take care of the church of God" > in 1 Timothy 3:1-10. So, if this is done right, it will work well. But ones have done the married pastor thing the wrong way so it has not worked, then they have blamed marriage!!
But priests take a vow of poverty, and most priests do not make even minimum wage for their hours worked. Trying to support a family on such a wage would be next to impossible, practically.
Paul our Apostle says he worked with his own hands to take care of himself plus he made enough to take care of those who were with him. This he did by means of God's grace, so this worked . . . as is possible with God. But people who do things the wrong way will have problems; and humans can invent thought-up problems to make a good thing seem bad or impossible to do . . . "instead of learning to do it right." And by God's grace, while he worked, he also was able to do all the ministering he did.
But humans don't do things in God's grace; so they fail, then make up doctrines and policies which accommodate their failure and weakness.
Acts 20:32-36
Philippians 4:13
Here is my "opinion" about why God gave us celibacy and holy matrimony >
Our Apostle Paul says >
"For I wish that all men were even as I myself. But each one has his own gift from God, one in this manner and another in that." (1 Corinthians 7:7)
And James says >
"Every good gift and every perfect gift is from above, and comes down from the Father of lights, with whom there is no variation or shadow of turning." (James 1:17)
So, I see from these verses that marriage and celibacy in the Holy Spirit are good and perfect gifts; but human counterfeits aren't!! God's grace makes you succeed, not bleed, in whichever is your gift. And Peter says that our gifts minister God's very own grace > 1 Peter 4:9-10.
So, celibacy is for ministering God's grace; and holy matrimony ministers grace. But I consider these gifts are specialized. Celibacy is for learning how to become intimate with God and do only what He personally guides us to do; a celibate gains growth and experience in this, while he or she ministers the grace of this to help other celibates but also married people to get closer to God. So, may be celibacy is the helper gift for our First Love Commandment to love God with all we've got.
Meanwhile, holy matrimony is the gift for sharing in a very close involvement with another person while growing in love . . . not falling in lust and infatuation and then falling apart in arguing and complaining . . . but grow in real love and do not fall, but grow. In marriage you are in a research laboratory in which you with each other make breakthrough discoveries of how to love

And then minister this ability to relate . . . to other couples, to ones preparing for marriage, and also minister to celibates to help them learn how to relate in love. So, holy matrimony is the helpmate gift for our Second Love Commandment to love others as well as we care for our own selves
