I think you are confusing the blank lineup (where the coach decides) with a lineup of no players that results in a forefit.
The problem is that if no lineup is entered then the game will use the default lineup that was saved at some time in the past. Sometimes that is a LONG time in the past and all of those players are long gone.
Personally, I don't know why everyone doesn't have a current default lineup. I find it much easier when setting my lineups for games. Most of the guys are in the right spots. I have to make a couple of tweaks for game shape, matchups and strategies. I have to rotate my trainees but most things are already as they should be.