Your friend's room probably feels more put-together without that random bold wall. I remember helping my cousin paint one wall dark green, and it just made the rest of the room look unfinished, like we forgot to buy enough paint. It created this weird focal point that didn't match the furniture, so everything else seemed dated. Cohesive design is about balance, and sometimes a single accent wall is just a shortcut that doesn't pay off. You see it in open floor plans especially, where one colored wall can chop up the space instead of defining it. Glad you spotted that, it's something a lot of people overlook in the rush to make a statement.