It is not. Here’s a quick annotated screen crop of a few texture toolpath segments viewed from the side (i.e. an edge view through invisible stock).
In this example, I’m just showing the first few toolpath lines starting from a very small part of the design, as otherwise the view would just be a solid mass of overlapping lines. If you were looking straight down along the Z axis, each blue curve in the illustration would be one straight line. Looking edge-on (parallel to the wasteboard), you can clearly see that each blue curve starts basically at the surface, curves down to some maximum depth, and curves back up to the surface.
The “Min Depth” and “Max Depth” settings in the “Texture” toolpath options set the bounds for randomly selecting each individual texture toolpath segment’s maximum depth. So, the actual minimum depth for each segment is the top, i.e. “Start Depth”, and the actual maximum depth is some randomly selected value between “Min Depth” and “Max Depth”.