I spent most of my life as an absolute assassination "buff" and conspiracy theory believer. I changed my mind after reading Posner's book ... which IMHO gives the best presentation of the evidence of any book on 11/22/63, and I've read 'em all, plus it digs out the fact that people knew Oswald was a ticking time bomb with violent inclinations as far back as junior high school and nothing was done about it ... and visiting Dealey Plaza and checking out the scene with my own eyes. I now believe Oswald did it and did it alone.
Bottom line, the reason people keep searching and searching and searching and digging and digging and digging to try to find out "what really happened" is that they simply can't conceive that a piece of human debris and flotsam and jetsam like Oswald could kill the most powerful man in the world just like he was plinking cans off the top of a fence. You put those two things on either side of an equation and it doesn't equate, and because of that people keep looking for hidden reasons, meanings, etc., and refuse to accept the simple explanation.
Run google for a search on Posner reviews, including a book entitled "Case Open." I don't know if that will move you back to a second gunman way of thinking or now, but it will show you that Posner was, at best flawed, and at worst, a hoax. The skinny is that Posner either ignored or tried to create a credibility problem for evidence that didn't fit his scheme. That's nothing new; I'm sure other JFK authors do that as well. But Posner is by no means the definitive work.
I don't think that's true. People have an overwhelming tendency to believe what they are told to believe. However, when the "tellers" consistently act as would someone who is highly motivated to sell you snake oil, even the most gullible become suspicious. People were told, from the first hours, before any evidence had been collected and analyzed, that LHO, acting alone, did the deed. Therefore, if there is a lot of disbelief much of it can be laid at the feet of the demeanor of the establishment in putting forth its point of view.
Having said that, I have also been squarely in the camp that LHO was a bit player (the Patsy) in a wider scheme. I revisit the issue at 20th, 30th, 40th anniversary. I will admit, probably due to the internet, that this time around, I have a far greater belief that the official story may be the correct one. Until this year, I gave zero credence to the SBT based, primarily, on the Z-film (it doesn't look like Connolly is hit in the necessary time frame) and Parkland doctors (whom I naturally believe more than a highly motivated establishment seeming to try too hard to convince me while being closed and secretive about evidence). While I still feel this way, I have seen many interpretations of the Z film to question my recollection/judgments, and I give slightly more credence to the position that the Parkland doctor's may have been confused.
My primary point here, however, is that the level of disbelief, IMO, has far less to do with your explanation, above, than it has to do with the behavior of the establishment in putting forth its version in a manner akin to a whitewash.