The entire premise is communal living. Shared toilets, showers, kitchen. Quarantining a dormitory would just be leaving everyone inside to get sick and recover, which does not sound humane.
All the dorms I've lived in or seen have no where near the kitchen facilities to actually cook for the whole dorm inside the dorm they were all fairly regular sized kitchens for a 2-3 bedroom apartment at best and didn't have a set of communal pots etc. in the rare case you wanted or needed to cook you provided everything.