Sweeping statements in biochemistry must be made with caution. It is well known that there are some small peptides that are absorbed following oral administration.

...BPC-157 itself is said to be among this class. As are certain milk tripeptides: https://en.wikipedia.org/wiki/Lactotripeptides

Interestingly enough, those two, as well as Gly-Pro-Hyp, are proline/hydroxyproline-rich, which might suggest that proline-rich small peptides are resistant to degradation in the gut.

Anyway, in general oral proteins and peptides are broken down prior to systemic absorption, but not always...