Stuff that takes up a lot of space, usually doesn't come packaged in a single file. It may be a single directory with subfolders and files, or it may be different directories spread around the file system. If you're looking to free up space, simply hunting for the single largest files, isn't so effective.

The question does say "files and directories".

Yeah I just wanted to keep the subject concise.

I guess the question title imprinted itself in me. Perhaps better off just rephrasing to "sort file system contents by size".

Added directories to the title.