Regarding historical evidence and how an argument based on that evidence can be presented, Prof. Goldsbury sets a high standard in his "Transmission, Inheritance, Emulation" series - definitely worth striving too.
This comes nowhere near, and neither does this
Off course that the thing that is being proven, and the position that is being held is never fully and succinctly stated allows multiple supporters to happily coexist without a need for any evidence whatsoever.
Hmm, got sucked back in...
I'm not talking about proving something beyond a reasonable doubt on an internet forum. What I'm asking for is that if someone says "this is what I'm calling Aiki" then they at least show some evidence of a link to what Ueshiba stated as Aiki. Absent that they can just say that they made it up, it's their own opnion, or whatever, and people can draw their own conclusions.
FWIW, the "investment" (emotionally, financially, in terms of their training etc...) that you talked about is, in my experience, mainly an obstacle among the conventional Aikido folks - the other guys tend to be more open minded and investigative about what may or may not be working and why.
Also, in my experience, Dan is much clearer and succinct about stating what he is and what he is about then most conventional folks (although it may not all happen on an internet forum), or is it them that you're talking about?