They failed because they increasingly took a political tone and pressed on alienating everyone center to right. You can't lose 50% of the possible audience and continue on.
I don't know that I believe this. Isn't it standard advice to go with a product that 50% of the market is excited about instead of one that 100% is indifferent about? Aren't Breitbart and Fox News doing very well for themselves alienating the other 50% of the audience?