There may be very valid reasons for leaving a congregation.
* I am aware of a SDA congregation in which members have transferred out due to the fact that the spiritual needs of their children were no longer being met in the one congregation. That is a valid reason. I have done that.
* SDA congregations engage in ministry. Some people transfer to a congregation that a form of ministry that they believe God has gifted them to engage in. I have done that.
* SDA members follow a wide spectrum of beliefs and lifestyle. Some congregations do not welcome members appear to differ from the common congregational members. I live near such a SDA congregation, one that would not welcome me as a member.