Information Overload's Bad Definition
Cohen's 'myth' concept seems to stem from people being overwhelmed by personal choices, and unable to meet their own unreasonable expectations. The solution: Cull your reading selections, match the time you have available with the most important sources, unplug a bit, and you'll reduce the possibility of IO even existing. Fair enough, and a good strategy.
The standard meaning or definition of IO is usually along the lines of "the state of having too much information to make a decision or remained informed about a topic". I don't buy it. Do we really think that it's human nature to be paralyzed by information? Well, most of the Librarians in the room don't. If we're running along these lines, then Cohen's right - it's a myth.
The problem for me, is that I believe that IO does exist, and it usually occurs when people have no clue how to match their interests with appropriate information sources. For example, I want to be informed about web technology trends in non-law libraries, so I read Cohen's blog. I could load up on sources similar to what he reads, but that's not core to what I do, and not a good use of my time. But what if I made a bad call, and did exactly that? To me, that's IO and it's such an easy mistake to make. Is it a correctable 'choice'? Yes, but it still exists.
My take, and perhaps simply a difference in definition, is that IO is the negotiation between information want & need, and being in a personal state of over-delivering on the 'wants'. If we have the opportunity to consume any information we want, most surely we will make bad choices (kid in the candy store & all...). Cohen is correct in stating that IO is not a passive process (or a state of the world, as the media might have us believe), but the vast majority of people cannot work backwards from their own gluttony of content choices.
Defining one's interests, evaluating sources, and selecting an appropriate number of sources are all vital; but learned skills that few people do well. If you define IO my way, honestly, I don't think it could possibly be a myth.