At 6m/s descent rate Mavic consumes about 4-5% of battery from 500m to 0 (test done at 4500ft AMSL). I didn't test at the default 3m/s (too lazy), but since it would take 2x the time, and the props spin at almost the same RPM (after all, if descending at constant speed, lift equals to weight regardless of speed; there are small differences in efficiency due to downwash and body drag), it's not unreasonable to expect it would take ~8-10% of battery. So if there was no 500m limit, and some pidiot (pilot idiot) flew it super high and ignored low battery warning (and disabled Smart RTH, too) and flew until 10% remaining, still at more than 500m up, Mavic won't have enough energy remaining to reach the ground via critical battery RTH and would fall out of the sky, possibly hurting innocent people or causing damage to property.
Just a hypothesis on how they came up with this seemingly arbitrary number - 500m - that doesn't have any analog in aviation airspace altitudes.
Just a hypothesis on how they came up with this seemingly arbitrary number - 500m - that doesn't have any analog in aviation airspace altitudes.