They're talking debt-to-disposable income ratio, which ChatGPT tells me means "Debt over in income after tax." I don't think this is necessarily descriptive of someone's financial situation. I'm over 400% debt-to-disposable income, but I could pay off my mortgage in a week if that made financial sense.
If you've got investments returning more than your loan rate costs you, I don't know why you'd pay down your loan any sooner than you had to.