Why is hiding the table tennis serve considered a foul?

It is a foul to hide the ball with your left arm when serving.
It wasn't like this before, but at some point, it became a foul.
If you think about deception in baseball pitching,
I feel like moderately hiding the ball during a table tennis serve could be considered a type of skill,
so I am curious why it was regulated as a foul.
Is it because the Chinese players are too good at deception moves?
Currently, all amendments to the table tennis rules are being made in the way Europeans want, in an attempt to beat China.