If you do the "bare minimum 140f once a day" method, you have to flush all the hot lines with this for long enough to kill it.
All this also presumes correct thermostatic calibration and generally even temperature distribution in a system planned to age with minimal maintenance.
The process isn't instant, you also have to ensure the hot water hits all the lines down the way at the appropriate hold temp and, well, hold it there for long enough.
These outbreaks still occur today. Not a huge problem, but why design such a well controlled hazard back into your potable water?
Where I am, you’re not allowed to deliver water to fixtures higher than 49C (120F), to reduce scalding risk. and this is usually accomplished through a mixing valve at the hot water tank outlet.
11m people live here, haven’t heard of any evidence of increased legionnaires:
All that other stuff assumes a minmax hot cycle in a waterheater tank.
On demand heaters work fine too.
I urge great caution, although I'd wager you'd be fine, so long as you remain healthy.