Oh my dear lord, you are being really, really stupid.
1. Your quote regarding football players proves absolutely nothing in relation to our argument. Why do you think football players are more prone to neurodegenerative diseases? Because they fucking run full speed into each other!!! What do you think would happen if they were not wearing helmets? They would be severely injured or dead within a short time!!!. In football, severe head injuries are relatively rare, deaths even more so, ergo, helmets protect your skull as well as your brain. You have actually managed to choose an example, that supports my argument. Great work, thanks for that.
2. Why do you fail to understand that to protect your skull is to protect your brain? How is this not logical to you? I think what you have gotten confused is that helmets will not necessarily prevent you suffering a concussion, however it can prevent you from suffering a cracked skull, and traumatic brain injury, and instead suffer "just" a concussion. Helmets are proven to prevent or lessen head injuries, when suffering a crash. Here's a breakdown of what helmets do:
"Helmets designed to handle major crash energy generally contain a layer of crushable foam. When you crash and hit a hard surface, the foam part of a helmet crushes, controlling the crash energy and extending your head's stopping time by about six thousandths of a second (6 ms) to reduce the peak impact to the brain. Rotational forces and internal strains are likely to be reduced by the crushing."
Basically, your helmet diffuses the energy, so that instead of cracking your skull and INJURING YOUR BRAIN!!! (See the link?) your helmet cracks. It's actually pretty simple.
3. "sure a helmet will protect your skull from cracking open on a rail, but it won't protect your brain at all on a 40 foot booter when you slam it into the ground." I cannot believe how ignorant this is, and it is mind boggling how you do not see the similarities between hitting your head on a rail and hitting it in a landing. There's not much difference, it all comes down to with how much force you hit your head on any given thing. You can hurt your head equally bad on both things.
4. It is so amusingly ironic that you would say that I should know what I'm talking about before I post, when you clearly have not even the slightest clue about the bullshit you're talking right now. It's so amusing, it gets aggravating.