Why can’t we access static content via uninitialized local variable?

§15.11. Field Access Expressions:

If the field is static:

The Primary expression is evaluated, and the result is discarded. If evaluation of the Primary expression completes abruptly, the field access expression completes abruptly for the same reason.

Where earlier it states that field access is identified by Primary.Identifier.

This shows that even though it seems to not use the Primary, it is still evaluated and the result is then discarded which is why it will need to be initialized. This can make a difference when the evaluation halts the access as stated in the quote.

EDIT:

Here is a short example just to demonstrate visually that the Primary is evaluated even though the result is discarded:

class Foo {
    public static int x = 1;
    
    public static Foo dummyFoo() throws InterruptedException {
        Thread.sleep(5000);
        return null;
    }
    
    public static void main(String[] args) throws InterruptedException {
        System.out.println(dummyFoo().x);
        System.out.println(Foo.x);
    }
}

Here you can see that dummyFoo() is still evaluated because the print is delayed by the 5 second Thread.sleep() even though it always returns a null value which is discarded.

If the expression was not evaluated the print would appear instantly, which can be seen when the class Foo is used directly to access x with Foo.x.

Note: Method invocation is also considered a Primary shown in §15.8 Primary Expressions.