Despite hailing the Post as 'the future of journalism', Keen, who was speaking at the Frontline Club debate 'Is new media killing journalism?', said the growth of such news sites was not a sustainable economic model for the industry.
The Cult of the Amateur author said technological advances were turning 'the media into the blogosphere' at the expense of accountability and paid-for journalism.
“New media doesn't support a viable newspaper business in the long term. It is not an economic system in which people who want to be paid for collecting and distributing information will be able to make a living,” said Keen.
“It is no coincidence that just as you have the rise of The Huffington Post that encourages people to give away their content for free you have job losses and the death of the professional journalist.”
Kim Fletcher, chairman of the National Council for the Training of Journalists (NCTJ) and Keen's team mate for the debate, said the traditional and 'important social service' supplied by journalists was being replaced with concerns about money.
The general secretary of the National Union of Journalists (NUJ) Jeremy Dear disagreed with the motion and said any threat from new media to the economics of the industry was the fault of the proprietors.
Journalists are having their skills spread too thinly to cover a range of new media platforms without proper reparation, because proprietors are returning profits to shareholders rather than investing in journalism, said Dear.
"The evidence demonstrates that new media has the potential to breathe new life into journalism and redefine it. There's ample evidence that user-generated content, blogs and online publishing can add to what we do. New technology is not the problem, its appropriation is,” he said.
The motion of the debate, which was held in recognition of World Press Freedom Day tomorrow, was defeated by 42 votes to 13.