I might be biased but having worked in a NICU for 8 years, I have seen GBS infections in babies and they are and can be very very nasty very very quickly. I understand if you don't like antibiotics as a precaution only but I couldn't take that risk. But that is just me. I have known parents take their bub to a naturopath after antibiotic therapy.
my own child was saved by antibiotics following newborn sepsis, but I still do not see his condition as a reason to treat all babies regardless. The risks are too big.

Also he did not have GBS, there are many many infections that can affect a newborn. I feel very strongly that more monitoring of babies and educating parents in how to spot an infection would be more helpful than mass abx treatments.