Funny, I bet more people know how to raytrace a sphere in software than know how to rasterise a polygon these days. Neither is terribly hard (or terribly useful, to the average dev.)
Even a single triangle is harder than a sphere, but with a triangle mesh you can't avoid thinking about acceleration structures and having a watertight intersection test, which includes worrying about floating point precision issues.
So what you're saying may be less about raytracing vs. rasterization and more about spheres vs. triangles.