Idk if GIMP has a marketing problem but I definitely agree that FOSS projects should add screenshots and a description of what the program does to their website and repo. It really annoys me when someone links a piece of software and it just doesn't say what it does and there's no screenshots that would make it easy for me to see what it looks like and how the UI is structured. When there's no screenshots I'm rarely even interested in trying it out because, even with a description, I don't really know what it is. Like, I wouldn't be interested in a car based on only a description, I'd have to see a picture of it too.