Allow me to start with a quick summary of this article:
There's a 270% gap in conversions between desktop and mobile, because mobile websites suck and we’re all doing it wrong. (Now that I’ve gotten that out of the way, I’ll explain why and what needs to be done to fix this.)
At its essence, responsive design is supposed to make a cross-device world a more seamless experience by adapting your desktop design to a smaller mobile screen. Unfortunately, condensing all that desktop content into such a small screen has the exact opposite effect — it's actually causing huge loss in conversion rates. But how?
https://moz.com/blog/responsive-design-fix-conversions/
Consumer habits are quickly shifting and more online activity is occurring on-the-go with mobile phones, netbooks, e-readers and tablets as opposed to desktops and laptops. Every device and operating system offers a unique user experience with specific functions, requirements and behaviours.
The Problem: Many business websites do not provide a smooth user experience on mobile devices. Users need to ‘pinch-and-zoom’ to properly view webpages, webpages are slow to load and site menus are difficult to access.
Not being accessible on mobile devices results in a loss of local website traffic, mobile leads, and potential profits.
https://greenlotus.ca/blog/responsive-website-design/