exactly I don't get where people think it's neck movement or even "nerves in the jaw"(bernard hopkins quote) that knock you out, you get hit, your head rocks, your brain suffers trauma, you either get wobbled or you go out. a strong neck helps with the stability if you do happen to get hit flush
its actually not nerve endings, its the brain again, other than the temple being hit and the equilibrium being disturbed, its all down to the brain, here's an experiment, make a fist, and tap yourself on the cheekbook, youll notice your head feels solid, now do the same, and tap yourself on the jaw, youll notice your head wobbles substantially, if you have a headache, this will actually make your brain sore. the jaw is loose, therefore getting hit on the chin/jaw, will wobble your head substantially more than say, a hit on the cheekbone will
let's take a recent example, look at Donaire KOing Arce, Donaire hits him right on "the button", but do you think it was nerves, or Arces violenty shaking head and traumatised brain that put him down?
Generally it's the opposite - a stronger neck means you'll move less and the brain rattles less, so you're better able to take a punch. There's a reason even the guys who don't lift weights still lift neck weights. I'd say its the main reason Shannon Briggs' beard got better when he bulked up, for instance. Of course, flexibility is important too, but only if you also have the reflexes. Keeping the neck flexible allows you to better roll with the punches, and thus not get hit as cleanly.