For some reasons they don't use the usb_otg, might it be they don't have the otg cable or something other, doesn't matter.
Maybe they aren't familiar with command prompt(command line), adb etc.
Q) What does this tool do ?
A) It let's you choose the desired rom, then checks if the device is connected and finally pushes the rom.zip to your internal storage.
Q) What does this tool NOT do ?
A) It doesn't install the rom.
You may add comments, questions, requests or graphic_design_help since my gui sucks badly.
Some prerequisites have to be met, adb driver should be installed. If you have ever rooted successfully that should be covered then