They are saying that if you need to leave the line you may get a return time - it all depends on the situation, such as party size, etc. They aren't promising anyone that the return time will factor in time spent waiting on line. When you ask why someone would risk waiting in line, the answer is because for the vast majority of guests it will be the only option. You seem to have the misguided idea that someone can just refuse to wait in line at all and the CM will be forced to issue a return time. That isn't the case.