they hang rugs on the wall because it is freakin cold and the furnace doesn’t work
it’s insulation
Russian centralized steam heating works extraordinarily well. You'll find yourself opening the windows in January to let some of the heat out! Interestingly, there's no thermostat. The heat comes on in the winter and is turned off in the summer. Everyone's heat.
The rugs are for privacy, to make it more difficult for neighbors to eavesdrop on your conversations.