How come peak electronic tendency work on 12V D.C., whilst household power rates 100-127V or 220-240V AC?

Take computers for example. The power supplies convert the source voltage to above all rails of 12V and 5V. The power supplies in computers are integrated, so that's not even the biggest problem. But 9 out of 10 several electronic devices are supplied with transformers: chargers for laptops and mobile phones, power supply adapters for big televisions, gaming consoles, even heavy power consuming audio sets. They all run on 12V, and 90% runs on D.C..

I do comprehend that high emf is needed to carrying current over long distances, because of the big energy loss a lower voltage will lead to. So I guess my question is: why not just use one converter where the electricity meets the household, instead of using all those hot adapters, bulky chargers and noisy right supplies?