At least with the electricity prices in Germany (not referring to the current price level, but with reference to the last decades), a dedicated source of heat (oil, gas, pellets, heat pump, district heating, …) is normally more cost-efficient than simple resistive heating.

So while it's true that that standby consumption is at least good for something in winter, a lower standby consumption and in turn turning up the central heating a little more would normally still be the better choice.

Very few people heat their homes with electricity. It's the most expensive energy source. So while the heat is atleast useful in the winter, most people would prefer to take the TV idle spend and apply that to a much cheaper heat source.