Let’s talk benefits of focusing on mobile first.
Identifying the most important content and building up
Designing for a smaller space first will make you evaluate your content and message in a new light. What do you want users to see first? Where do you want to direct them? What content can you cut from mobile and have only available on tablets and desktop?
Doing this will create effective and efficient messaging, allowing your user to quickly gain the information they need to make an informed decision.
Beauty on all devices
A mobile-first approach focuses on providing the same experience on desktop and mobile. Rather than cutting down a beautiful desktop site to fit mobile, you can make mobile beautiful and equally informative and then build up to the desktop.
Reversing the design process allows you to provide a better experience for all users.
Google’s Mobile-Friendly Algorithm
Google has released that it will now be boosting the effectiveness of its mobile-friendly algorithm (read a statement on the webmaster blog here). Many factors go into this algorithm; however, designing for mobile first can help you avoid penalties altogether.
Focusing on speed, readability, and effectiveness of your mobile content will help your site be in good graces with Google across all platforms.
Is this approach right for you?
The true answer depends on your user base, content, and other factors.
If your user base is 75 percent desktop, you should focus on desktop and move to mobile. But if the opposite is true, take the mobile-first approach.
In the end, the design approach you take is largely based on what is right for your clients and users.