Powder coating directly on metal makes it very hard to damage this build plate. If a heated nozzle crashed into it, the metal can dissipate the heat. Powder coating also gives the surface a distinct textured look that will be visible on your prints.
The textured surface hides most of the mechanical damage caused by tools. Only the top of the small bumps can be scratched, which will not imprint on the bottom of the model.
This surface is used on our print farm, look at the printed parts you have on your printer for reference.