I think the biggest obstacle to getting started with flexbox is not being able to picture how to use it, because you’re stuck thinking in terms of what was possible with floats and other old layout methods. It was the same when we switched from tables to CSS layout, and from fixed to fluid layout—you had to make a mental shift to start thinking in terms of the new possibilities and approaches to old problems.
Flexbox lets you do lots of things you haven’t been able to do before, and some things you could do before but now in a simpler way. Once you see what flexbox can do in the real world, you can start picturing how to use it in your own work to solve real RWD problems today. Flexbox can be tricky to wrap your head around at first, but once you’ve learned it, it’s an incredibly quick, cheap way for you to add more responsiveness to your components.