By revewing the code of the tools gives, a newbie gets a
"jump start"
on learning how to code a web page from scratch.
In other words,they start learning CSS AND HTML codes just
by reviewing the code in the out put of the tools.
The Good Part: By playing around with various input values and
then viewing the source code it's possible to learn
a lot about basic HTML codes By viewing the source code,
a newbie will learn as they make changes to the code.
And it will Improve your W3C validation,And help google to
Index your site.and have a search engine friendly website.