The way I have understood the documentation I have read here is that they favor unprocessed, or lightly processed images. It does make sense they expect the people to be shopping for images in Adobe Stock to probably be people who actually own Adobe products already, and the market for images that can be manipulated is probably higher than for those that are already manipulated.
Something that would be neat would be to allow for an image to have child images, that are manipulated versions of the original.. these could be more expensive, the person who submitted the original image would still get the commission for their image, while the person who made the manipulation could get a smaller commission. If you did both then you would get both commissions. Unfortunately something like that would probably be pretty hard to do.