A humiliation ritual, an act of submission to the more powerful people controlling showbiz.
Imagine if you get your butt poked by your master, do you dare to go against him in future? He can threaten to expose your dark secrets or do even more terrible stuff to you.
Many famous people literally sold their souls to the devil. Like forced to engage in pedophilia, so they leave 把柄 for them to control you. Or forced to sacrifice their family members, many cases of their family member die under "mysterious/suspicious cause", or forced to transition their child to other gender. Not just artistes but also politicians. Ex-PM of Canada Justin Trudeau, Current PM of Canada Mark Carney are examples.
Do not idolize anyone.