I found this kind of a very odd statement. Isn't the event horizon a consequence of the stuff going on underneath? The image I have in my mind is of water drain

I found this kind of a very odd statement. Isn't the event horizon a consequence of the stuff going on underneath? The image I have in my mind is of water draining out of the tub and wanting to strip off the top layer of water to see what's "going on" inside the whirlpool, when of course stripping off one top only reveals another and so forth.