Because someone posted some code using the [ code ] [ /code ] tags. When you use that tag, it keeps the formatting of the code that you enter in it. It doesn't wrap it.
For example the following line of text is gonna be put in the code tags and you will see that it won't wrap unless I put a break in the line.
This is a line of text to show that the [ code ] [ /code ] tags keeps the format of the text/code line break that it was entered in and doesn't wrap this text.