I've been wondering the same thing. The only thing that I've been able to come up with is that maybe the wheel wears faster under certain circumstances using these settings. I can't figure out why that would be, though. In any case, as with all undocumented features, the unexpected may occur.
Yes all can be happening, like Fanatecs CSW wheels on full FFB and 0-deadzone + centering spring maxed means month to two life time.
Reducing FFB somewhere near 5 and my wheel is much cooler than using on "normal modes", and I don't have to worry at my wheel is going to die.
Logitech probably wants to save their asses from situations where customer is putting all maxed and drives some 24h-race on gravel with it.
Personally using FFB=5, Powersteering ON, Sensitivity=5 or 6 when using O-mode(670°).
Sensitivity 7 and FFB 10 would make nice for warming up room, not suggesting to use so high FFB