The world got really complicated all of a sudden. You see it in life and you see it especially at work. While so many great applications exist that simplify life's transactions and advances in technology make a 24/7 layer of connectedness, there is a cost that we have incurred as a result.
Adopting the "design first" philosophy, however, forced us to approach the design of our system through the lens of what our intended end users wanted -- whether or not it aligned perfectly (or at all!) with our goals.
It's undeniable that mobile is where people are. They're posting, commenting, sharing, and buying. If you don't think this affects you, please take a look into your website's analytics and get an idea of how many visits you're receiving from mobile.