The Drivers score is a method created by Productboard and it is thereby not a well-known formula such as established prioritization frameworks. However, for new and small companies Drivers can be something to start out with because it is very simple to understand and easy to get started with using the 1-5 value, as opposed to having to define your own value ranges first. Again, it depends on company size, product, org., etc. what is the best fit, which is why we open up for more flexibility with the Formulas.
For more information, see the article Create your own prioritization formulas