Printing directly on the platen can be useful, but dimensional accuracy suffers greatly (Z is undersized, and X&Y are oversized) due to the compression layers that are designed to be used only by the support base. The laser curing profile is also different at these layers because making the base stick to the platen is the primary objective, than up where the part typically starts, so some over-curing will occur which will tend to make the final part a bit more brittle.
That said, this is still a great method for removing the base from the platen. Cool 