I suppose a site could trick me by making their fake popup look exactly like the real one. But in that case I would tap Block and be no worse off, other than seeing the same notification again the next time, at which point I would probably figure out their trick.

I thought of explaining this to some friends to help spare them some needless popups, but decided it was too complicated and would likely just confuse them. This is not an insult toward my friends, just a reminder that something that seems simple to you or me may be very puzzling for most people, no matter how intelligent they are.