To make it simple, you can directly use the portable package on your USB drives.
For example, you’re a IT service provider and everyday some customer would like to resize C drive because of the low disk space problem, with the portable edition on your USB, you don’t have to download the program again and install it and finally run it on custom’s computer, you just plug in the USB drive and open the software, it will just do the same as the installed one.
Besides, most users would not like to install any programs on their computer again when they’re here to free up more disk space.
The portable edition is also widely used on server side computers, in big companies with many pcs in different departments, with one partition software on one single USB, an administrator is able to manage all the computers with ease.