Many explain that Gemara as Davka applying to Avraham Avinu because if he had a daughter she would have to marry a Goy and her descendants wouldn’t be part of Klal Yisrael
Source? That is certainly not the Pashtus in the Gemorah.
I have heard it is written in the K’sav Sofer B’shem the Rambam that the reason that the Rambam explains was due to the hardships of finding shidduchim for daughters (as the Ramabam says he personally had), due to the shidduch crisis of 900 years ago.