The culprit? Native driver support.
Intel's Windows 7 USB 3.0 Creator Utility - Level1Techs Forums windows 7 usb 3.0 creator utility intel
Since the official Intel tool is deprecated and potentially insecure, many users turn to alternative methods for modern-day Windows 7 builds: The culprit
It modified the boot.wim (installer environment) and install.wim (actual OS) files. windows 7 usb 3.0 creator utility intel