It's like that story about robbing the bank. First, we get jobs at the bank. Then we go in and work the jobs every day... (spoiler: we never actually rob the bank, because we get cushy jobs with benefits, and retirement plans. That's brilliant!)
Anyone with a good credit score can decide to burn their credit at any time. Loss prevention can also step in and cancel your cards at any time if they decide that you've gone off the deep end. They probably won't... but they could.
Imagine Google made its own credit score, based on your searches, social contacts, etc. It turns out that someone clicking on ads for product X have a very high likelihood of repaying their debt. This information ends up publicly leaked.
What do people start doing? How does this affect the quality of Google's credit algorithm?
It shows that the person is planning ahead, is careful with not overspending even if they have cash available, is organized enough to make all the monthly payments on time. To me that seems like a better signal than someone who does need the loan.
How would a person who takes out the same loan, but actually spends the money be a better credit risk?
This leads people to do something they don't want to do, and is no more informative than paying all those other bills would have been, merely to increase their score. That's a kind of gaming.
If the way they have allowed you to "game" this metric results in you signing up for some credit in order to improve your credit score, that's nothing but a net win for them. They got you some credit, that's definitely a score for them.
(I'm not saying that credit card companies would prefer all of their customers to default, they would never be able to buy insurance again... I just want to put it out there that maybe the system works exactly this way, 100% deliberately, because it benefits them too.)
A reliable indicator of whether you will pay your bills in the future might be whether you paid your bills in the past. There is no way to game this metric, other than by paying your bills.
You just chose a metric that would be easily gamed and said that any metric is gameable.
Except the exact situation outlined above, in which a person generated bills that they otherwise wouldn't have needed, for the sole sake of having more bills "paid on time".