Existing fingerprinting mechanisms to identify client devices on a network tend to be coarse in their identification. For example they can tell it is an iPhone of some kind, or that it is a Samsung Android device of some model. They might look at DHCP information to know its OS, see if the client responds to SSDP, or check DNS-SD TXT responses.
By examining Wi-Fi Management frames we can identify the device much more specifically. We can tell a iPhone 5S from an iPhone 5, a Samsung Galaxy S8 from an S7, an LG G5 from a G4. This talk describes how the signature mechanism works.
Specifically identifying the client is the first step toward further scanning or analysis of that client's behavior on the network.