One of the key points of CI is the number of libraries and helpers that help us in our site development. You can find HTML helpers, pagination libraries, image libraries, and a lot more easy-to-use and very powerful code. As always, we as developers decide whether we want to use them or not; CI isn't going to force us, though it is always a good idea to use them. For example, you can write this line of code:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
Or use the HTML helper and write:
echo docytype();
You obtain the same result. CI has lot of helpers and libraries that will help us write less code, write it faster, and hence, be more productive.