Blame that on another unintended consequences of the one child policy. I can't blame those parents much. I have 4 children, but if i was forced to have only 1 child, i can also imagine i would also spoil that child since he will be the only offspring i will have on earth, the only one i will leave behind after my death. It's normal there will by default be a higher probability that he will be more spoiled than if he had siblings. Lol Luckily i have 4(one already moved out not long ago (over 19) now, so of course things are different.
To be bonest, if i had just 1 child i will never even allow him to join the army/military for example. I dont even know how those parents who have onlh 1 child and that child joins the military, cant imagine how the parents will feel so worried in case a conflict ever happens.
So we have to also put ourselves in their shoes,and as a parent i know how that feels.