אין בן דוד בא עד שיכלו כל הנשמות שבגוף שנאמר: רוח מלפני יעטוף ונשמות אני עשיתי
This directly contradicts the later concept of gilgulim, if understood literally.
Chazal clearly held (according to this pasuk) that each person is a new Neshama that needs to come before Ben David.
One of the purposes of having so many children, is to bring down all the remaining Neshamos.
Any gilgulim at all, if understood literally, would be against Chazal (besides for having no basis in Torah or Chazal)
Some people try to reconcile this by interpreting gilgulim as being a “bechina”, some connection, but not literal. (like a candle being lit by another flame)