http://andrewgelman.com/2016/09/21/what-has-happened-down-he...
What you're left with after consuming the work is a single giant "fact" that's actually composed of a whole bunch of genuine knowledge and a whole bunch of nonsense, and it's mentally draining to toss the nonsense because it feels like it's somehow a key part of something valuable. The big cohesive viewpoint is a lot more seductive than the actual truth - that all of the material needs to be evaluated separately and there are no shortcuts for sorting it out.
Or another way to put it: You really need to keep a critical eye towards each new fact that's introduced, but the entire appeal of this sort of thing is the idea that it's all one super-fact, so your critical thinking is at odds with your desire to enjoy the big picture.
At least with a good book you get an expanded argument, for or against which you can argue yourself. These feel-good pages, as I call them, are as good as a fart against the wind.