Brewster can't be blamed for taking the job in the first place , he was coming very close to the end of his football career and clubs were not exactly clamouring to employ him as a coach or manager after his abysmal stint at Tannadice. Nor can he be blamed for clinging on to his job now as he's unlikely to get another in football after compounding his disaster in Dundee with an almost equally poor spell back in Inverness.
It's not even his fault that he's a poor manager and tactician. I'm sure he does his utmost to be successful but that it just far from good enough.
Responsibility lies with the board, they were the ones who opted to re-employ him as a manager after his dire failure at United and they are the ones who see fit to continue to keep him in a job now when his lack of ability is being exposed week in week out and is in danger now of dragging us towards relegation and financial disaster.
If the board do not act quickly and decisively then any ill that befalls the club as a result will be their fault and nobody else's.