When the FBI tried to duplicate the shots, they needed to add 3 shims to the scope to even hit the target. A sharpshooter would NEVER use a misaligned scope, especially if he planned to assassinate the POTUS.
So, the answer is no, it would not have been impossible to kill someone with that MC, however, hitting a moving target 2 of 3 times including a headshot at 88 yards, looking thru the wonky scope of a crap rifle is so improbable we should be able to rule it out, like Wecht does.
As usual, CTers focus on the misaligned scope. We don't know if the scope was misaligned. However, I think it almost certainly was misaligned.
But this ignores the alternative. What about using the iron sights?
* The iron sights could have been used instead of the scope. The scope did not "block the view" or prevent the use of the iron sights.
*Oswald was trained in the Marines to use a rifle with iron sights. He never received any training using a scope. He was able to hit a human size targets at ranges of 200, 300 and 500 yards, using iron sights.
* While Marines are only trained with stationary targets (it appears to be impracticable to train thousands of recruits at once using moving targets) they have proven time and time again to be proficient at hitting moving targets in battle.
* The Marines at Guadalcanal used the M1903 Springfield rifle, with iron sights, with great effectiveness, even against moving targets, Japanese infantry charging at greater speeds than the limousine at Dealey Plaza.