I was careful with my wording: 'direct illumination' - point xenon/LED directional flash at target, shoot, enjoy off-axis vignetting, severe distance limitations, extreme inverse square contrast effect, & sharp nearly-incident shadows. Reflectors ('umbrellas'), big diffusers, aiming the flash at the ceiling, all the hardware that the places you mentioned sell, are aimed at avoiding these effects while still controlling the light quality.
Amateur photographers don't know this. They use on-camera flash because their cameras force them to use flash to get a reasonable signal to noise ratio. For them (who will never even attempt to use specialized flash diffusers/reflectors), the best option for dynamic indoor & evening scenes is a bigger sensor camera, or if they want to get really fancy, aiming a speed flash at the ceiling.
Much of the lighting I do is very much direct lighting; softboxen and other play-it-safe modifiers have their place, but you couldn't emulate, say, Karsh's style with them. And the inverse-square law is your friend, not your enemy. Light is merely a tool to get the shadows in the right places.
Amateur photographers don't know this. They use on-camera flash because their cameras force them to use flash to get a reasonable signal to noise ratio. For them (who will never even attempt to use specialized flash diffusers/reflectors), the best option for dynamic indoor & evening scenes is a bigger sensor camera, or if they want to get really fancy, aiming a speed flash at the ceiling.