As computers become smaller, and data get bigger, we got more and more storage space and constantly producing more data to fill them: You can take 10 photos per second using an iPhone 6. You probably won’t do that people are taking dozens of selfies from different angles and at different times just in a concert, vacation, etc.
Problem is, when you have thousands of files in your drive, it becomes impossible to manage them. First of all, you need to locate the file before using it. Think about it, why you need to locate a file to access it? You know what are you looking for, but you don’t know where it is. When did you (last time) walk through a categorized index of web sites to find the web site you are looking for? This is basically what you do, when you try to find a file in a (hopefully, categorized) hierarchy of directories in your file system.