Why we need most of the time develop a new website using html only?

The main issue is there is no ready made functions or codes are available to perform certain functions, for eg. if we need to sort something we needs to write long query to sort these

they are child developers. you can use php , java , many of many language have . if you use any language with html, you will see better web page. 

During web design period, a time spent in html desining is a good design.

Browsers only understand HTML, whatever other languages used has to convert to HTML for getting output from the browsers. All the websites has to use HTML and most of the websites are static websites which only use HTML.

Browsers understands html only its a front end development 

HTML is the core for web bases programming, and interface is the most important thing in any development as the end-users have to easy-use your web page. But with HTML burger and similars, you don't need that big time anymore

Indeed it is the foundation of website development but I will include DHTML for alittle dynamism and maybe add some CSS or java scripts to take it to the next level.