Perspective. The z-axis creates 3 dimensional space, and the z-order of objects in that space determines which ones are closest and farthest away from you.
You see this on Microsoft Windows, as the z-order is why some windows are “on top” of others while some are hidden. A little geeky, yes, but look at it this way: some issues in life are closer to you than others, and the closest ones can obscure others, blinding you to them. If used right, z-order is to your advantage. If not, it can destroy you.
Commitment issues. The first one was very difficult to work with and abruptly quit when he went too far and was confronted about his behavior. The second one waffled on doing it for a long time, forcing a continuing search that finally led to a third singer just as the second one finally agreed but was replaced. The third guy had personal problems that made him unreliable and he sort of just disappeared. The fourth guy stalled until his life situation changed and he couldn’t do it anymore. The fifth guy had a hardship befall him. Like many of them, the sixth guy thought that taking forever was okay but we decided his voice wasn’t working for the music anyway and let him go.
Those songs were added more than a year after James and Dave did their parts, so Randy just did them. It was easier and all of those songs are acoustic guitar, where Ellefson feels less need for Dave’s bass riffing and could handle the easy drums.