I weigh daily, and I can't say that I really think there's any good reason for it, except that I can't stop.
I've never heard of someone who weight loss follows a perfect downward slope. There are just too many variables. Salty meals or sore knees might make you retain water. Or hormones. A little dehydrated and you might be lower than you should be. Weighing yourself daily isn't a problem, but thinking you can actually
use the number you see, I think that can be dangerous. My pattern is to lose about 5 lbs in a couple days, and then bump around near my new low for a couple weeks. I'm not doing anything different, it's just the way it works, and I could mess myself if I thought I could tinker my way into keeping the loss more steady.
I agree with the graphing idea. As long as you're seeing a downward trend, you're good, and the bumps along the way are meaningless.