Though I understand the term "arm chair magicians" to refer to magicians who have loads of theoretical knowledge, but very litttle direct contact or practical experience, I believe all magicians can benefit from a balance of study and practice. The metaphor that comes to my mind compares the practice magick to gastronomy.
I have collected cook books since I was about 6, and books of magick since I was a teen ager. I have dozens of both. Though I have never formally trained as a cook, I have an abiding interest in good food, and received a lot of on-the-job training from various kitchen jobs I've held. I supported my learning by reading culinary magazines and studying cookbooks. From these I have received both technical instruction and creative inspiration. But I havem't cooked every recipe that I have, not even half of them. I haven't used every technique. My day to day diet doesn't tend towards the gourmet either, though I am able to produce much fancier, more elaborate food than I eat every day.
I think the same is true for magick. At a certain point, you have to stop reading the cook book and get in the kicthen and start breaking eggs. Regardless of your skill level, you have to be able to feed to yourself. The cook book, the Food Network, the glossy pictures of "Bon Apetit"–all of these can help support your cuisine, but they cannot feed you. With magick, you can read all the theory that's written, but unless you take the steps to align will with action, until you begin to practice with your head and heart and hands all engaged, somethign is missing. Theory is incredibly important, but assimiliating it is essentially a passive act, which engages only the most cerebral parts of one's being. Without action of some sort to engage the self on more than a conscious level, one's study of magick will be lacking.