Hive weight changes every day. And every change means something, if you know what to look for.
When bees start bringing in nectar, the graph moves upward, or at least stops falling. From how fast it rises, you can see whether nectar flow is strong or weaker. The end of nectar flow is just as readable. Weight stops rising and starts to stagnate. There is no need to open the hive and no need to be there.
Swarming has a characteristic shape in the graph: a sudden significant drop from one day to the next, sometimes within hours. If you were not at the hive, the scale captures that something fundamental happened. In autumn and winter, weight slowly falls in proportion to store consumption. If it drops too fast, it is time to look at why.
A sharp drop outside nectar flow can mean robbing. A sudden unexplained change can mean a fallen hive, animal interference or another problem. The scale does not tell you what happened, but it tells you that something happened and exactly when.