We have L8s without giants. They regularly beat girls WITH giants. We had 1 compete Saturday and she was 2nd place out of all L8s on bars (and AA).
If it is a kid’s near-to-last season or near-to-last level, it is fine to pull out all the stops (so for that reason, it’s good USAG doesn’t actually require Giants—I stand corrected), but for girls who may want to keep options open (many do) it seems like “no giants” is the beginning of the end.