70% of internet users are viewing websites on their phone; and if your site isn't built for mobile devices, you're limiting your potential customer base.
The slow loading time of your website can make visitors come in and out within seconds. A slow website is not something to be ignored, as this can deter people from sticking around on the site for more than just a second or two.
Websites with no clear CTA tend to result in higher bounce rates. A call to action is any way of getting yourself or someone else doing something, and it's the key ingredient for driving conversions on websites from visitors who are just browsing around.
Google is the king of search engines and without keywords to optimize your content for them you basically made a website that's off the grid.