One thing that really annoys me on Wikipedia is when a poor newbie makes a new page or adds some text to an article, or course without having an understanding of MOS, NPOV, or other core policies. It is simply rollbacked, and the user gets a warning. Of course, this upsets them, and they react with anger. They just get more warnings, without ever getting an explanation or reason, and if they aren't blocked, they are so upset that they leave Wikipedia forever. This really is injustice, and despite violating IP!=VANDAL and PDNBTN, it really happens all the time. Please, rather than just giving a CSD notice and warning them for personal attacks when they try to contact you, explain to them what they did wrong and why it was deleted; even better, help them re-create it along wiki guidelines.
Another thing to remember is that editors are valuable. They are not expendable. I see it happen so often that people get pestered for every little mistake, while not being given credit for all the work and time they put into this place. It's really sad when someone spends a year learning the ropes and starts really doing great work, then someone carelessly insults them and they leave Wikipedia forever. Keep in mind that editors can leave at any time and if pushed, they will.