Sure one can find all sort of arguments why this is, but it still violates the principle of least surprise. I don't think anyone would go and say, "oh this is an icon view without clear order, so I should not be able to select a group of icons".
It doesn't violate the principle of least surprise if you're basically inventing the convention, which is the case here. There's a slightly different convention in some subsequent systems but they typically don't have arbitrarily positionable icons. The MacOS convention has been around for nearly 40 years.
