Wasn't it Sam Snead who said something like, "A golf course is a terrible place to use your mind", or some such thing?
I think Brent and Lou are pretty much on track, especially for the guy who is trying to visually memorize a golf course in terms of details, numbers, features, etc. That's enough of a job for anyone and then trying to play a very difficult game at the same time can be daunting.
That's why I believe a really good player like Tom Paul now generally prefers to just walk a course to see it architecturally, as opposed to playing it. There have been multiple times when he's come along with a group I've been playing in, walking with just a putter and a few balls. Of course, he's also had to suffer by watching my sputtering game while studying the course, so perhaps he hasn't gotten the true architectural benefit he might have otherwise.
For my part, and even though there is some self-deception in this statement, I guess I realized about 5 years ago that no one is paying me to play this game, and when all is said and done, the difference between 75 strokes and 90 strokes is really not all that we make it out to be. So, I try to do the best I can on each shot, but I'm really there to be as much an observer as participant.
Unless I'm playing somewhere I've played a couple of times, and involved in some type of match, I'm really just taking a walk in the park, hitting a ball along the way.