It is just Wallpapers are not stock, they are for using on your monitor. As long as they are used as wallpaper that is fine. But not as stock for people to use in making their own pictures.. there is plenty of stock on deviantart and other stock sites that you might use.
Yes thank you I understand the nature of wallpapers and then how they spread to other sites and works. Have you done a search by image to see where all your work ends up. It is like the childs game of Telephone. By time it gets to someone or back to you the original is distorted and lost. Regardless, thank you. Your images are lovely and I see you are quite a successful professional. I think it is great you allow free personal use, I truly do and no offense or challenge was ever intended.