The constant call in the New Testament is towards believers attaining maturity. Ephesians 4:11-13 sets out that maturity is one of the core purposes of ministry gifts. 'Christ himself gave apostles, prophets, evangelists, pastors and teachers, to equip his people for works of service, so that the body of Christ may be built up until we all reach unity in the faith and in the knowledge of the Son of God and become mature...' Similarly, Hebrews 6:1 calls out '... let us move beyond the elementary teachings about Christ and be taken forward to maturity'.
'Maturity' is seen as a key sign of making great progress in Christ. Leadership is a key way of supporting believers to get to that point. Yet to hear many church leaders speak, one would think that leadership was the end point and the real sign of maturity-to an extent that there is almost an unstated implication that to have reached one's 30s or 40s and not be in some form of leadership must be a sign of immaturity.
Some leaders have tried to get around this by arguing that everyone is called to be a leader and set this out as being leaders in terms of being an influence in the community, in being an influence at work etc. The difficulty is that the New Testament doesn't see being an influence as being a sign of leadership. It just sees it as part of the normal expectations of being a follower of Jesus.
This emphasis on a leadership role being the key mark of maturity also has an effect in churches narrowing the pool of wisdom by which theology is shaped and decisions are made. It means that discussions on key issues which would be benefit from the wisdom of a variety of mature Christians are instead only informed by a narrow group of people in a church leadership role (and in saying this I must also emphasise that I believe that it is biblical and right that decisions on key issues are made by church elders. It is the benefit that could be gained by mature wisdom informing those discussions that I am highlighting).
The other attitude that can flow from equating maturity with leadership is an implicit assumption that someone who is not a leader would either not be interested in anything beyond day to day church life or is in danger of stating something heretical if they were given a voice (and, if that really was a constant, regular danger, one would have to ask what that says about the quality of teaching and discipleship in the church in question!).
Again I come back to emphasising that Christ appoints leaders and gives those leaders gifts and wisdom for the roles He calls them into. In no way do I want to detract from that, but I also believe that the body of Christ is what it says on the tin-a body made up of all who are in Christ and all who are called to be mature, with all the implications which flow from that.