They have to accept the limitations of the process they chose. I don't want them to keep trying to make grape juice out of apples. However, if the OP is looking for an actual circle (or cylinder) in the model it is not how polygon file format like STL or a process that uses those models work. With enough polygons the difference from a perfect circle will be smaller than the capability of the machine to make it.
I don't disagree that you can get smooth surfaces from polygon models. What he hasn't really outlined is where he's taking the model to when getting the model 3D printed. Some of what you can get for jewelry and lost wax casting is just mind blowing. and very little to none shows in terms of facets. Not to 100% disagree with you on where you're going with this, but it is possible to get a very smooth surface with with various AM processes.
