Scaling model from meters to mm only changes precision in model’s units, but the precision in real millimeters stays the same, so the units don’t matter.
I think they avoid millimeters because down the art pipeline people who’ll use the models expect meters, e.g. to place the stuff in a metric world without extra scale involved.
The units do matter though, since the absolute float value is what determines your precision.
The author of this article translated by 200k units, so the precision loss is relative in this case. But artists might need to translate something 100 meters, so their precision loss depends completely on their choice of units.
If an artist needs to translate a model 100 meters off center, and the model is in meters, the graph you’ve linked says the precision will be 10^(-5) model’s units, which is 0.01mm. If the same model is in mm, the graph says the precision for 100*1000 will be 10^(-2) model’s units, which is the same 0.01mm.
As you see, it's independent on the choice of units.
Edit: this translates to 320m if you want 0.01mm precision.
The number's the roughly the same even if you'll model in km or imperial units.