Your link has John O'Shaughnessy being interviewed by Barry Ritholtz (two respected folks in finance), and O'Shaughnessy later corrected himself:

* https://twitter.com/jposhaughnessy/status/115517108366392524...

While I do believe set-and-forget passive investing is best for the vast majority of people, last time I checked that Fidelity study does not actually exist, and the story is apocryphal (no one seems to be able to actually link to it).

If you ask Fidelity about it, they'll tell you it does not exist:

* https://www.morningstar.com/columns/rekenthaler-report/archi...