Thanks for the tutorial link. But I still don't see the need for so much watermarking if you are only shooting pictures of a board game you want to sell. Hi-res or not, I can't see anyone wanting to hang an image of a collectible board game on their living room wall
But then again, who knows what some people will do for decorating their homes.
If it were fine art and you were trying to market the images, then maybe. Even then, I would go with one tiny watermark and a lo-res image.
But I guess it boils down to individual choice.