A community loss can become your bill
If an association suffers damage or a liability claim exceeding its insurance, it can levy a special assessment on members to make up the difference. That is a direct personal cost arising from something that happened to shared property. Loss assessment cover on your own policy pays your share up to a stated limit.
The association deductible can also be assessed
Master policies often carry large deductibles, and some associations pass a share of that to owners after a claim. It is a smaller figure than a catastrophic shortfall and it is far more likely to actually happen.
The default limit is usually small
Where loss assessment cover is included it is frequently a modest amount, often a thousand dollars or so. Raising it is generally inexpensive, and in a community with substantial shared amenities it is worth more than the default suggests.