It's a combination of factors. Having debt itself isn't as important as payment history, age of accounts, etc. Credit card debt is probably the opposite of helpful; paying off a card every month in full for a long time is much more useful.

Credit balances don't negatively impact credit scores as much as one would think. It's ultimately a combination of factors that go into an overall credit score with the heaviest hitter being payment history. If one makes all of their payments they can have a decent credit score despite carrying a 10k balance. Carrying a balance of greater than 30% of the limit will detract significantly from the overall score, but it won't knock it below "decent" range on its own.

I'm honestly not even sure how one actually gets their score below 500. My wife got a head injury and physically could not remember whether or not she'd paid her credit cards a couple of years ago, so they ended up becoming delinquent and going to collections. Ultimately it dropped her credit score to about 500 but then it started climbing back up from the car loan and mortgage that are in both of our names and is almost up to 700 again. I seriously want to know how people manage to get their scores down to the 300s (the floor is 300) because you basically have to try in order to get your score that low. A friend of a colleague managed such a feet and then had some identity theft which actually improved his credit score because it looked more like normal credit activity than his real credit activity