What are you going to do when you're in a tournament and you have a few bad holes? Part of learning disc golf is learning to deal with a few bad holes.. keeping score will test you with that.. I've seen some people getting totally PO'ed and refuse to play anymore.. there's no way they'd do good in a tournament setting. I agree that there are times when it's not necessary to keep score (working on a particular aspect of your game) but there are also times you should keep score. It shouldn't be all or none.
Believe me, anytime I play, there are usually at least a few holes where I do badly. My argument is that knowing the actual score doesn't change anything. I just try and remember what shots worked and what shots didn't, or what holes I did badly on, and why. I generally only keep score when there's something riding on the outcome, and keep a cheat sheet of what I need to work on otherwise