1) Weber may have claimed on his deathbed that he was Dan Cooper, but there are no other witnesses to that alleged statement.
2) Weber cannot be linked to any verifiable parachute experience. And no one in a sane state of mind would attempt leaping out the back of a moving 727 without at least some prior experience.
3) None of the stews or witnesses have even HINTED that Weber could be the hijacker from pictures.
4) The physical evidence, if any, is lost or otherwise unaccounted for.
5) The witness who said handwriting in a Cooper book was Weber's has retracted her story, or refuses to confirm.
6) Weber cannot be positively placed in the NW United States at the time of the hijacking.
7) None of Weber's ex-wives or other family members have offered definitive evidence leading to the possibility Weber was the hijacker.
8) Occam's Razor might suggest that with so many previous arrests and the extensive hunt for the hijacker, that Weber would have been discovered reletively quickly.
9) Weber's occasional behaviors, (if true) such as tossing a bag off a bridge and taking his wife on a NW trip and dropping hints...might suggest he was living a fantasy and secretly wanted to be Cooper. Most of his life he was a loser. Maybe he wanted to be a winner, and used his wife to further those ends. If this is true, it only shows he was selfish and sentenced her to a life of endless hunting for a truth that was never there.
10) The FBI did an obviously thorough investigation and may have discovered the same things.
Side Note: Picked up my new Nissan truck today. You know where I will be for the next few days: Camping, fishing, hiking, shooting, guitar. Too much work, too much travel lately.