You can use it for either predictive or explanatory purposes. In the early ('00s) years of Google it was common to diagram out the incentives of all the market participants; this led to such innovations like the use of the second-price VCG auction [1] for ad sales that now make over a third of a trillion dollars per year.
> It’s important to note that our move to a single unified first price auction only impacts display and video inventory sold via Ad Manager. This change will have no impact on auctions for ads on Google Search, AdSense for Search, YouTube, and other Google properties, and advertisers using Google Ads or Display & Video 360 do not need to take any action.
[1] https://en.wikipedia.org/wiki/Vickrey%E2%80%93Clarke%E2%80%9...