Good markup is search engine-friendly
Only content free from formatting can be easily repurposed
The use of font element or inline CSS fuses content and formatting together. By turning off the CSS on your Web site, you can see if your content is free from formatting and if it can be easily repurposed in a different page layout, should you want to redesign your Web site in the future.
Content is king
Are visitors attracted to your Web because of its quality content or because of its pretty layout? By turning off the CSS on your Web site, you have the opportunity to see what you are really offering your visitors - quality content!
Search engine-friendly markup
Search engines are blind - they don’t see the pretty formatting on your site. By turning off the CSS on your Web site, you have the opportunity to see your Web site in a similar way to how search engines see it. Making sure your Web site works well with CSS turned off will make it easier for search engines to process your Web pages and will lead to a better search ranking.