I like to see all files in my Dired listings but lots of folks have a more minimalist mindset and would prefer not to see certain files. Things like backup files, .DS_STORE (on MacOS), or even all dot files are examples of files you might find uninteresting.
If you’re in the latter class of Emacs users and you’re using Dired-x (which you really should be) you can easily prevent certain files from appearing. You can specify files to omit by either regexp or by extensions. Check out this reddit Emacs post for the details.