The only valid reason for planting a new church is to evangelize a community and make disciples from new believers. But you would be surprised how often churches get planted for other reasons - to “teach” every week, to lead a revolt against another church, to satisfy ones ego, to do something with prestige, to educate Christians, or to have a title.
But without a real passion for sharing the Gospel with an unbelieving community, (Jesus called them “scattered sheep having no shepherd” Matt. 9:36), church planting is futile. Without the courage to preach Christ crucified to those who do not yet believe, it’s purely recreational.