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.
I visited a friend in Russia in the 90s. She said Moscow apartments were absolutely airtight— no cold seeping in. So the rags must be for the privacy. Also, maybe they need to let them air dry after using them, since they probably don’t have washer/dryer hookups in apartments? Finally, for years Russians had to paint walls with whatever color was available, so maybe throwing a few rags on the wall helped to hide a gross color.