I think what he means by G0 surfaces is surfaces with a million fully multiple knots.
If you take any simple well-behaved single span spline curve and use it as input for ExtrudeCrvTapered the result will be a surface with a gazillion control points and all the surfaces knot spans will be fully multiple. Users have been complaining about this for 25 years.
There are lots of ways to work around the mess that ExtrudeCrvTapered produces.
The users are always expected to be more competent than the developers. The users can fix the mess but the developers can’t.
ExtrudeCrvTapered typically produces a good result if the input curves are tangent lines and arcs. For any other input it usually produces a mess.