BazookaBaboon

Greetings! I'm looking to build a neck-through bass, why does nobody seem to make some kind of joint between the neck and the body pieces (dovetail, tongue in groove ect)? I've read that in theory, a guitar made from a single piece of wood would have more sustain/better tone. Applying that theory, a joint between the neck and the body pieces would make the instrument more solid, resulting in better sustain than two planed pieces glued together flat. ... So why not do that?