Why websites should be Mobile Responsive?

Every Single person is now connected with mobile phone and operating the many of things using mobile. The important thing is like when we open any website on mobile the should be operate it like the desktop and easily operated by user while operating on phone.

If we consider that 100 people are their using our website then as we observed that 80 percent people are being operated with using mobile phone that's why the reason every website should be mobile responsive.