Well, it's not that you can't handle them, it's just that less is better. Sometimes you have to handle them, cage cleaning, mating, taking them outside, taking them to the shower, photos, etc. But, it is stressful to the animal, which a lot of times leads to interesting color patterns that people like to take pictures of. So, if someone were to take a poll (hint, hint, moderators), you'd probably see that most experienced keepers handle their chams once a week or less.