"modern wolves are not dogs' direct ancestors"

Another study like this also found that at the time of domestication dogs had a genetic change which allowed them to digest starch (cooked grains).

The genomic signature of dog domestication reveals adaptation to a starch-rich diet

I'm not willing to say human scraps are more or less healthy than scavenging carrion or the weakest (possibly sick) animal in a herd. BTW offal has more nutrients than muscle meat.