Do you have a camera that has a usable ISO 1600? (Hint: if you're using a full-frame camera of recent vintage, the answer is "yes". The answer is also "yes" for a goodly number of smaller-sensor cameras these days.) If you do, and you also own a "full sized" on-camera flash (Nikon SB910, Canon 580EX/600EX RT, or an approximate equivalent, whether your camera's marque or third party), you have an available guide number of at least 230 in meters or 770-ish in feet. (The farther away, the more zoomed-in your flash can be.) And you can double those numbers when necessary if you're lucky enough to have one of those cameras where ISO 6400 is just another setting. "Too far away" is a long, long way away.

And if you actually read what Neil has to say (and look at the occasional behind-the-scenes shots he posts), you'll notice that he'll take advantage of just about anything. You don't need a massive expanse of white wall nearby; a post or ceiling beam will do if there's no wall handy, as will exterior concrete, tablecloths, the shirts of willing "assistants"... If all else fails, you can always go off-camera.

As for the bounce from above, it's the vertical or forward bouce he's talking about. That puts the light directly or nearly directly overhead. Basically it's high noon on a slightly overcast day; the raccoon eyes are a little bit softer than you might get with direct sunlight (or with direct on-camera flash as your main light) but that doesn't make it flattering. He will use a ceiling bounce behind himself (and to the side with individuals, couples or small-enough groups) when he needs to.

Yes, that throws a lot of light away, but you have a huge excess of light with a speedlight when you're not battling the sun (or trying to use a too-low ISO because you can see OMG NOYZZES!!! at 100%). Let's say you lose three stops on the bounce, mostly because of the bad angle bouncing behind. At ISO 1600, that leaves you with a GN of about 40 (meters) from the bright spot on the wall (or cieling, or what have you). That's f/4 when the bounce surface is 10 meters/33 feet away from your subject. Doing the same thing with grey concrete, or at an ISO of 800 instead of 1600, means you'd need to be at f/2.8 at the same distance. Or you could lift your ISO to use a smaller aperture or handle increased distance.

Neil isn't leaving anything out; you're just vastly underestimating how much light a modern speedlight puts out when paired with a modern DSLR. The days of GN36/120 flashes and shooting VPS or Portra 160NC at 125 are far behind us, as are digital cameras that need to be kept nailed to ISO 100.