Putting aside the endless contrarian loon arguments, why would any conspiracy plan involve bringing the president to the assassin instead of the assassin to the president? That is sheer stupidity. It's idiocy to believe that the plan was to put a patsy in some random building and then manipulate the schedule and motorcade of the president to bring him by that specific building. Much easier to control the movements of the patsy than the president.
Strawman "Smith", right on cue. Why would a single designated patsy have to be chosen, and chosen in advance?
This just the same old argument, take 100001: "This vast Conspiracy I made up in my head would never do something like X. Therefore there was no conspiracy. Therefore, Oswald did it."