I had perfect FICO on Experian 9, for months. When I paid off the house? It dropped 16.
Does anyone think to themselves, who cares? It's not like one's blood pressure or cholesterol, it's rather meaningless actually.
In other words, imho the algorithm is like UTQG in the tire business. By design, it's to reward the lender or the tire mfg.
Although nobody truly knows how FICO works, I think we do, based on so much observation. If one owes a lot, and one pays back regularly, the score goes up. But imho having a perfect FICO is no reason to go into debt.
Of course, someone will likely step forward and say I have perfect FICO and I have no debt. But all I can say is again, paying off the house and having the loan discharged, caused my FICO to drop 16 from 850.