In the Boy with a Kite script, the page states "We see...but we do not hear..... What we do hear is ...."

This passage specifies not only camera but sound / editing. In my days of peer advice, this passage would have been criticized by some for "directing the scene." Judging just from the passage itself, I think the conventional wisdom isn't particularly wise. The writer isn't so much trying to give directions to some hypothetical director as setting the movie in the mind of the reader. It works for me, and I can't imagine a studio reader being offended at such a "liberty."

As you're pointing out, there is an evolution in terms of what a spec script can do in terms of telling a story. This is not to say that the older methods were faulty or the newer methods are superior, but just that a writer who keeps up with trends (as opposed to worrying about fossilized rules) has more opportunities at hand for creating a compelling spec.