Before, the DVD disk is used for install windows. It also takes more time to install. But the main problem is the possibility of scratches. Which will create problems during installation.
But after the availability of usb drives, all those problems are solved. It comes with different capacities. So that you can easily create a multi bootable usb drive.
There is no chance of scratches. So it gives you the benefits of longevity. Also, the installation process is faster than the DVD drive.