100% agreement there, TeeEmm, althought the g/a ability of reduced power is a nice one to have. BA even USED to teach selecting ARM in the last stages of a manual throttle s/e approach to make the g/a 'easier' in strict contravention of Boeing's rec. Lawyers' benefit as you say.
In my time RHS I have seen a Captain flare too high with ARM and the TOGA function kick in (with humerous results), and also you will find an ACCURATELY flown Vref+5 at some F40 settings (a rare event!) will trigger the TOGA reversion as it can be just below 1.3Vs at some weights..
Any input on the original query?
Denti - you must have a later Training manual than me!
Mine says (my bolding)
Autothrottle Use
To simplify thrust setting procedures, autothrottle use is recommended during
takeoff and climb in either automatic or manual flight. During all other phases of
flight, autothrottle use is recommended only when the autopilot is engaged.
Autothrottle ARM Mode
The autothrottle ARM mode is normally not recommended because its function
can be confusing. The primary feature the autothrottle ARM mode provides is minimum
speed protection in the event the airplane slows to minimum
maneuvering speed. Other features normally associated with the autothrottle, such
as gust protection, are not provided. The autothrottle ARM mode should not be
used with Non-Normal checklists. Some malfunctions that affect maneuvering
speeds cause the autothrottle to maintain a speed above approach speed.