You can draw any object with fragment (aka pixel) shaders. Because some specific math techniques can be used to draw shapes, regardless of the technology (SDF, trigonometry, ect).

So some talented artists are pushing the bounds and wrestling with performance trade-offs in the fragment shader.

Fragment shaders are more commonly used for making full screen filter effects (color correction, ect).

Shaders are also used to make textures and materials on basic objects. Material artists often generate textures with shader math.

Many visual effects are made by using shaders in creative ways.

Shaders are run on the GPU in a parallel, wave-like fashion. Many, many, many threads run across the same data in one wave.

In some cases shaders are much faster than CPU branching code. Shaders also have easier access to some rendering data.

So they are a good space for creative special effects.

Any object in a game with a high level of surface detail is a common target, to shift that detail onto a shader.

Ocean surfaces, tesselating meshes, ect.

There's many other uses, because GPUs are powerful and flexible.