you are right, the more surface area the faster it will rot or give out, however, a proper box/finger/dovetail joint is sealed properly and doesn't have more surface area, really. I make box tail, though I could just as easily make dovetail joints, and I use my router. I can do ten sides of a box in as much time as it takes for me to move the router across them, move my jig to the next position and do it over again until I'm done. it goes fast, honestly. very fast, and it is very clean.
I also assemble on a jig I made, which makes sure it is flat and square, and it is as simple as putting the glued sides (I use tightbond II, but have used tightbond III also.) up and brad nailing them together with my airnailer. though I've used staples also. tap, tap, tap,tap, tap next side until its done. then wipe off the joints, and its done.