The problem with learning from media (be it a book, cooking shows, a website, YouTube videos, etc), is that it's pretty much one-way communication.
You can't get immediate responses if you have a question. (wait, let me set this aside, ask on the website, then go back to cooking 3 hrs later once I have an answer), and there's no one there to give you hints that maybe you're doing something in a less-than ideal way.
Yes, you can learn a lot by trial and error, but that means you don't have the collective intelligence of even one single person's years of experience. You can watch for differences in how someone dispatches a bell pepper (I think Rachel Ray has finally switched over to the faster method of taking the sides off, rather than trying to scoop out the inside) or other techniques.
Some books are more informative than others. (eg, Cookwise explains a lot of why the recipe is the way it is ... but then again, it was written by a chemist) and many of the "old classics" cover techniques and such, rather than just be a list of recipes and maybe some cute stories about the author's childhood and pictures of what the dish could look like.
So, in summary : you can learn from a book, but it's less than ideal; your skills will improve faster by cooking with someone else with experience, or even watching videos for techniques.