There are different opinions. I've formed my own opinion about it by talking with (mostly) guitarists about it - the common theme is that those who say they started playing by anchoring have big trouble unlearning it. One guy simply wanted to unlearn it because he wanted to play the guitar behind his back now and then, rock star style.. the anchoring got in the way and he couldn't fix it. If you learned to play without anchoring the hand it's easy to play behind the back or neck or whatever - at least not very difficult.
If you, on the other hand, learn to play with the hand free, then you can anchor later if you wish, without problems. But first you have to learn to play without anchoring. That's easy enough if you start that way, but gets more and more difficult the longer you have been playing with anchoring. So, if you learn without anchoring you can later play in many more ways (including anchoring).
The general rule: You must learn the rules, _then_ you can start breaking them. So my advice, for what it's worth, is to learn to play with the hand free, learn it good and proper so that it feels natural. Then, and only then, can you anchor now and then if that helps for particular things. However, if you learn to play with the hand free you'll also find that you won't really feel much need to anchor for just about anything. But you'll see Jake do it now and then (but only occasionally. I bet he didn't learn playing with anchoring from the start.)
-Tor