Related to your question, Tapered Extrusion is similar to 2D offset curve: the result of offsetting a generic curve will have much more control points.
You will have the same amount of control points on an offset curve only with particular cases like a straight line or perfect arcs/circles.
Similarly, tapered extrusion needs to add more control points (the isocurves you see, denser) to make the correct surface.
If you need a less dense output surface you can lower the tolerance of your document, but it’s not a wonderful idea…
Or, you can split/rebuild your initial curve to simpler segments, tapered extrusion will result in many but maybe simpler surfaces…