All resorts have closed areas within resort boundaries. Some are roped off areas without CLOSED signage. For instance at bottom lift stations where just loaded chairs need clearance from passing skiers. Or snow measurement corrals where the resort doesn't want people disrupting measurement equipment and mucking up the snow. Or CLOSED and or roped off areas where streams flow lest people break through bridging snow and fall through into ice cold water. Many more resort inbound features may be so roped off.
And then there are areas people might expect to ski that can be dangerous before a ski patrol team assesses and clears hazards, especially in avalanche areas. But also where the unfamiliar guest might end up going into rocks. Of course a constant task of patrollers, especially in early season is marking obstacles on actual ski slopes and until that is complete, whole runs may be roped off. And then some resorts have inbounds areas that are permanently CLOSED like The Cirque at my resort Kirkwood. Well actually it is open and used for the annual extreme skiing championship event.
At large Western ski resorts where storms can dump multi feet of snow, many zones may never be roped off but rather only signed as CLOSED every minor bit of distance down a slope because the frequent snows tend to bury ropes. Thus one will see such CLOSED signs up on larger conifers and all experienced skiers and boarders become familiar with that system and know it is not ok to go between such signage even if they might find a spot where they cannot see two adjacent signs. It is up to them to check adequately.