I suppose the reason why no touring pros do this is because they have such a good mental picture of the hole that they don't HAVE to physically look.
When Tiger says he "takes a mental picture" of a putt and then "putts to the picture", he is, in effect, looking at the hole in his mind's eye and seeing it just as well as if he actually looked at it physically.
All pros have always stressed the importance of strong mental images and the power of the mind's eye, so it follows that there is probably a direct correalation between being able to visualize really well and being a good player, maybe it's more important than swing mechanics?