Linked paper [0] correctly states that QWERTY wasn't designed to slow typists down, but authors argue that it was not designed to avoid type-bar jams, but only vaguely suggest some letters were moved around due to Morse operation practice. They base that conclusion on analysis of radial distances of common digrams on typebar basket. But there's no justification why only angle criteria was considered, and they omitted that layout clearly minimizes adjacent typebar digrams, which is shown by [1] and [2].

They also without much evidence reject idea that TYPEWRITER ending up on same row was intentional design, but curiously enough [2] calculated odds of that occurring randomly as about 1 in 2500, so it might have been.

[0] https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433...

[1] http://widespacer.blogspot.com/2015/11/the-hidden-secrets-of...

[2] https://cyber.sci-hub.se/MTAuMTAxNi9qLnJlc3BvbC4yMDEzLjAzLjA...