the only goal of the DBS is for NO3 reduction to N2 gas.
We tend to dose and add KNO3 for a NO3 source and over time, low or high tech methods, planted tanks run low/limiting on NO3 very often.
A deep sediment for planting is fine.
But DBS offers you little else and displaces a great deal of your aquarium volume with sand, instead of plants, hardscape etc.
In other words, it offers no benefits, but does no harm either.