Easier to blame imaginary shorts, than focus on the real problems with these "companies". And since the shorts don't exist for the most part, they make an easy scapegoat.
In addition to the margin requirement, there's the simple fact that shorting has the opposite risk-reward profile compared to "long" so there's much less incentive to short.
Long: Infinite gain potential, 100 % max loss
Short: 100 % max gain, Infinite loss potential
"It is easier to fool someone, than to convince them they have been fooled."