Because it is washable. My wife also wanted it like that on a wall in her plant room. I also said that it is dirt. Didn’t help. Latex paint on silicate does actually flake off eventually. However, in our case in such small particles and also with rather heavy wear on the wall (I have a daybed in the office where I often lean against the wall to stream on the monitor). Because that makes the wall dirty in the long run, I only painted a small strip with latex paint to make it easier to clean there. After about a year, the latex layer had rubbed off in some places. But as I said, that is with daily leaning... I would rather recommend to the person asking the question to stick a robust washable wallpaper there. Pattern or photo ([funny would be a photo of the dogs]). Firstly, the stains are not so noticeable there, secondly, you can really wipe it off without worrying it will flake off eventually.