Some say it is for worship--but I can worship with my family or a group of friends. My entire life is to be characterized by worship.
Some say it is for evangelism and missions. Jesus did come to "seek and to save that which was lost" after all. But, we have so many other organizations that are so much better at doing this than the church.
Some say it is for fellowship--but I have much deeper fellowship with my family and with my tight circle of friends than I do in the broader congregation. There is a much deeper level of accountability and prayer support there as well.
Some say it is for discipleship. I'm not persuaded this happens very much at all, much less at church.
Perhaps the question goes much deeper than relevance.