iPhone 5s: benefits of 64 bit processors if no more than 4 GB of RAM?

My understanding is that the (main) reason of having a 64 bit processor, is to be able to use more than 4 GB of RAM. In PCs, it is now very common to have more than 4GB of ram, and to really be able to use such ram, you NEED a 64 bit processor. But for a smartphone, which (afaik) doesn't have more than 4GB of ram, what's the point? what is the benefit? What kind of apps benefit from it that will really make a difference ? **Specific examples of apps taking advantage would be nice.** Do final users will even notice a difference? Or is it just a marketing strategy? Note, i know a similar question has been answered here: https://superuser.com/q/56540/152803 but in this one i ask specifically for smartphones, that one is focused on Intel/AMD architecture. Besides, that answer is now more than 4 years old...