This is a common misconception. Credit scores are actuarial risk, not profit utility. Having some debt load is a portion of that equation because it basically prevents dividing by zero. This is very basic actuarial science - you cannot produce a risk/utility metric without actually having priors, and within those priors there's a concept of Fisher Information, which measures the likelihood that some sample of a random variable reflects true information about an unknown parameter. Simply put, the more information you have, the stronger the model. So the more debt you manage the more information about your debt management practices is available to the actuary. Up until the point that you have too much debt that it becomes very certain that you are high risk. If you have little credit history, but that history is perfect, you will still usually be in the lowest risk tier, but that might be like 780 instead of 850, or whatever, and that's merely a reflection of certainly within the model, not your actual behavior. A person with similarly perfect behavior, and a lot more of it, should be intuitively seen as a lower risk.

If that’s the case my debtless ass should have a much lower score. I’ve paid off a bunch of loans (mortgages, car, etc) and have <1% utilization now. Credit score just stays high.

I think it's more accurate to say it's a measure of risk , but it leads to the same result. Good, consistent repayment history means you are a known low risk. Without that consistent and recent history you are an unknown risk. Giving credit to low risk borrowers is where the profit is.

There are many paths to earning profit for a credit issuer. Debt traps are one of the more predatory paths. Some credit issuers want to issue high rated bonds that provide low, but safe, income over a long period. Some don't get profit from interest at all, high-end reward cards, for example. I haven't paid a penny of credit card interest in decades yet I'm issued cards that provide me with over $20k in benefits every year, these companies make almost all of their money off swipe fees charged to the merchants and partnership deals.

It absolutely is "a measure of how likely are you to pay off your debt", because that is "a measure of how likely you are to earn creditors money."

It's not some grand conspiracy. It's a record of previous behavior to predict future behavior to determine if you fit their business model.