The confusion in many articles on the subject is because both the myth and the truth argue that QWERTY was designed to prevent hammer jams. The reason this confuses people is because anecdotally many people find QWERTY slower to find keys ergo many laymans assume QWERTY was designed to slow typing down to avoid jams (in fairness, it's not an unreasonable piece of logical deduction even if it's not technically accurate).
The reality was that typists were trained to type on QWERTY so they weren't slow typing on it. What QWERTY was designed to do was move common follow on characters further away from each other so the hammers jammed less often thus allowing trained typists to type faster than they could have on an alphabetized layout.
The reality was that typists were trained to type on QWERTY so they weren't slow typing on it. What QWERTY was designed to do was move common follow on characters further away from each other so the hammers jammed less often thus allowing trained typists to type faster than they could have on an alphabetized layout.