I don't think I have every seen a tackle that was by the hair only. I doubt any player purposely tries to tackle someone by the hair anymore than they purposely try to facemask a player.
you guys forget about the '70'swhen lots of players had long hair hanging out behindtheir helmets. For those of us who played football at a post high school level back then , i cannot ever recall anyone grabbing hair to tackle someone. Grabbing hair is the least effective way to bring someone down. i suspect that is the reason why we never see this form of tackling occur. i have never seen it on t.v. in all my years watching. it is not a problem nor will it be. end of discussion.
I would like to think it would be a judgment call on the refs behalf. If it seems like a player is going for jersey but comes up hair, you gotta let it go. If it is blatantly deliberate I would think unnecessary roughing, potential ejection, potential fine or suspension.