I could see bead blasting if you want an especially rough surface after parkerizing, and bead blasting followed by solvent makes for an especially clean surface to make certain the surface gets chemically altered.

The parts we did in production, perhaps were not as aggresively rough as with bead blasting, as after painting, they appeared smooth. But before painting, they went from smooth typical mill finish, to a dull non-reflective surface after phosphoric acid bath. Again, were that not the case, gun barrels would not need to be plugged on both ends before parkerizing, to prevent roughening of the chamber and rifling.

The knife below, previously shiny as new, was treated with a very mild phosphoric acid solution (Ospho), mild enough that a spash on the hand is no problem, and while I wouldn't call it rough, the surface did get etched. If what you said is true, it should still be shiny. The previous production parts I worked on went through a much stronger acid dip, and were more deeply etched and phosphated.