just incase this isn't sarcasm, glue is stronger and more reliable than nails, it wont lose over time, bend or pull under the weight, glue spreads the weight out over the entire joint evenly instead of just a couple stress point. and a glued joint properly done is stronger than the wood its self meaning the wood behind the glue will break before the glued joint would, the nails are to keep it in place and kinda clamped together while the glue dries ( ideally I would want a bit more clamping force than a single brad nail ) and the list goes on I didn't even scratch the surface as to why glue can be the preferred or better joining method in a lot of situations, but not always, each project is different so never limit your self to just one or even only a few ways to join something verity will insure the strongest possible joint with many styles and designs options to give you the look you want