Grumbling on "How to Read a Book"...

.. from Chapter 1!

I will start by quoting the related paragraphs from the book directly, all strong emphasis mine..
Perhaps we know more about the world than we used to, and insofar as knowledge is prerequisite to understanding, that is all to the good. But knowledge is not as much a prerequisite to understanding as is commonly supposed. We do not have to know everything about something in order to understand it; too many facts are often as much of an obstacle to understanding as too few. There is a sense in which we moderns are inundated with facts to the detriment of understanding. 
One of the reasons for this situation is that the very media we have mentioned are so designed as to make thinking seem unnecessary (though this is only an appearance). The packaging of intellectual positions and views is one of the most active enterprises of some of the best minds of our day. The viewer of television, the listener to radio, the reader of magazines, is presented with a whole complex of elements— all the way from ingenious rhetoric to carefully selected data and statistics— to make it easy for him to “make up his own mind” with the minimum of difficulty and effort. But the packaging is often done so effectively that the viewer, listener, or reader does not make up his own mind at all. Instead, he inserts a packaged opinion into his mind, somewhat like inserting a cassette into a cassette player. He then pushes a button and “plays back” the opinion whenever it seems appropriate to do so. He has performed acceptably without having had to think. 
Van Doren, Charles; Mortimer J. Adler. How to Read a Book (A Touchstone Book) (Kindle Locations 165-176). Touchstone. Kindle Edition.

My Notes

The following proposition caught my interest..
But knowledge is not as much a prerequisite to understanding as is commonly supposed. We do not have to know everything about something in order to understand it; too many facts are often as much of an obstacle to understanding as too few.
especially the emphasised part. It is interesting, I wonder how too many facts can be an obstacle on understanding something?

So the book claims the reason why 'too many facts can be an obstacle' is..
One of the reasons for this situation is that the very media we have mentioned are so designed as to make thinking seem unnecessary (though this is only an appearance).
Here 'very media' refers to radio and television. But I simply do not understand this statement. I am trying to rephrase it for a better understanding, but without success.. Let me illustrate: "Too many facts are an obstacle for understanding, because radio and television make thinking unnecessary". Does it make any sense to you?

When one claims something like 'too much information makes you understand a subject more difficult' and goes on with "one of the reasons..", I would expect that sentence to finish with an outcome of a scientific study.

Help Wanted!

Is the author just suggesting that information gained from the very media she mentions just fills us with useless information? So the information we gain from television and radio is an obstacle to understanding, because it is rotten information, that encourages us not to think? Or am I reaching too far?

If you do have an opinion please share and help me understand. Thank you!