A couple thoughts come to mind.
First, it's not uncommon for someone who creates mental material to create a version of the material specifically geared towards magicians, in order to sell more copies. It's my estimation that very little of what's in the magic market is actually used by "real" mentalists. Which is because "real" mentalism isn't flashy or appealing to magicians. One could, if they focused on certain skills, do an entire evening show of genuine skills in mentalism, no deception at all. Magicians would hate it, but the right audience would love it. I posed this idea on the cafe and the response was amusing, to say the least.
Second, once one understands the "rules" behind the idea of mentalism and magic, one can effectively break those rules. This is a big part of why I constantly emphasize that the major difference between mentalism and magic is the theatrical approach/motivation behind them.
A mentalist can have "magic" effects in his show and still be considered a mentalist - because the overall theatrical approach is different. Just like a magician can focus entirely on mental effects if he likes, and still come across as a magician, if he has the theatrical approach of a magician.
The specific material is important, but it's not the defining characteristic between mental magic and mentalism.
A lot of what Derren Brown does is classic magic. But even many laymen call him a mentalist (if they are familiar with that term) or mind reader. That's due to his character and his theatrical approach to performance.
Somewhat unrelated: Playing cards have been used for fortune telling longer than Tarot cards. The tarot cards just have more of a "universally known" history of it. When I was doing Tarot readings some years ago, I actually had a guy tell me about how his family taught him to read playing cards. I can't recall what the relation was, aunt or grandma or mother or what, but it was an interesting system involving a yes/no question, and the suit of the card and value determining how close to an absolute answer it was. It was a really fascinating system and I wish I could remember it all more clearly. Also the dude was this big Hispanic biker looking guy. NOT the type of person you'd expect to be reading fortunes (unless you're familiar with brujos I guess).
