How useful is the creation of folders for your computer

Depends on your operating system. For any system not Chrome OS, folder creation is an organizational must. Your hard drive stores data sequentially in the form of bits. Whenever you want to access information on your hard drive, the drive has to, much like an array in programming, run through all the data until it comes across the desired file. This, as you could probably imagine, is cumbersome. We, as the users, have the luxury of not having to deal with that kind of information acquisition. We can create folders and directories into which we can place files. The reason I mentioned Chrome OS earlier, was because Chrome OS stores just about everything in the cloud. There isn't any real need to create directories on a Chrome system because all of that data can be managed and stored on Google's servers, as opposed to in files and organized by yourself.