There's a lot of truth to this, but....... fuck they did a great job disincentivizing it.
In high school we had to read and annotate this 900p Greek mythology book during our summer break. Our grade reflected how well we annotated it. I didn't do any of it (thanks Ultima Online).
The very first in-class assignment we had that year took about an hour and had about a 25% bigger impact on our grade than annotating did.
Not saying that grades are the end goal but it felt like a slap in the face that the exploration of such a deep topic just.. didn't matter.
What kind of abusive high school gives a 900-page summer assignment?
One that wants to teach Greek mythology but can't because no child left behind forced teachers to teach the standardized tests over all else.