I guess that for a lot of parents the saying is true. Most 'normal' parents by nature would do the best they knew how for their children. Some are clearly better than others. However I'd say that I was not alone in having two selfish parents. I don't know for sure I can say that of my dad but my mother still hasn't stopped thinking of herself first and the alcohol can no longer be blamed.
It can really upset me to hear people say that for many reasons.