I just stick Dracaena and similar plants directly into the soil where I want them to grow. We get so much rain, all the soil is moist all the time.

So Dracaena would be fine with having its stem buried, whether there are roots on the end or not.

What would your benefit be to plant it deep?

Two benefits that I can think of. One is purely visual, it would give a shorter, thicker stem for a while. It would also allow me to plant three at different depths and get a staggered appearance from plants that are actually about the same size.

The other benefit is, hopefully, functional. During our summers we get plenty of rain and through the rest of the year we get rain off and on, but the winter and spring months are kind of our 'dry' months. I also live on a sandhill, so I have 'extreme' draining soil. I have been adding organic material for a couple years now and it retains moisture a little better than it used to, but it still drains quite quickly. I am hoping that by deep-stem planting, I will put the roots that have already formed down into cooler, more moist soil that takes longer to dry out than the top few inches, so it wouldn't be quite as susceptible to a dry spell if I forget to hit it with the watering can (I don't usually, but it does happen).

makes sense!