Because Ms. Powers would rather retain control of the company at the cost of wiping out shareholders than relinquish control and make shareholders a profit.
This is not supposition but proven by how she was willing to smack Neil Woodford in the face when he asked her to start reforming corporate governance.
I think we all know we would be a lot better off if she had worked more cooperatively with Mr. Woodford instead of causing him to stop investing.
Naturally the only way management apologists can explain this away is to invent yet another conspiracy to bring down NWBO, this one with Neil Eoodford (their former hero) as the arch-villain.