Mobile-only websites versus responsive websites

A couple of years ago I was given the opportunity to build a website for an insurance company. The website was modern, and it had many features. Even a user was able to customize and purchase an insurance policy by spending a couple of minutes browsing the website. After launching the website, the client realized that he had an excellent opportunity to enter the mobile market because back then, mobile browsing was in its early stages. So, the following month he contacted us and asked us to build a mobile version of the website.

When we read the requirement, we realized that the mobile website had a similar functionality; only the UI was going to be different. So, we used the same codebase that the desktop version had, and we created a new website using the existing code. This was a popular method at that time, and the mobile website had a different URL. Once the user entered the original website using a mobile device, our script detected the...