Think there's more to it than just a blanket statement of certainty.
We'd need to see more TI specific info but the article below makes sense from a technical point of view when considering internal pack historical parameters are used for 'self evaluation'.
The article suggests that there is increased Fuel Gauge accuracy by an occasional deeper discharge. This may be more an issue for those who do not discharge to consistent levels such as random and sometimes frequent shallow discharges from short flights.
Since the art is continually improving DJI's reasons for discontinuing the suggested practice may be more financially (warranty, etc.) motivated than technical.
BU-603: How to Calibrate a “Smart” Battery – Battery University