Yeah, that's all fine until a year later when some asshole dings your fender and you need to repaint it and have to try to match it. No thanks - I'd prefer a paint code.
Any paint shop can mix a paint and after that they will give you a code with the formula.
The paint on the car you pictured is a pearl and even with a code it will be a large blend to get a ding to look like it didn't happen.