Quote Originally Posted by bitpicker
France, Britain (or at least England), Russia had long been actual nations with an aristocracy the language of which was seen as the 'standard dialect'
. . .
the Tsar's Russian, not the King's French, the Queen's English
What a worthwhile idea. In the 20th century the media (news, movies) were entirely Moscow based products. Spreading over the vast Russia's territory this makes all the Russians to speak equally.

Here is one specific to Russia point to add. Just at the begin of the 20th century there was the Russian language reform which changed the alphabet and brough many logical rules into the grammar. Of course all this made any sense only for educated people, which amount (just after world war I and 1917 revolution) was very negligible. But new Russian government (yes, those people from 1917) made an incredible thing using their unlimited power they EDUCATED all the Russian people. As far as the "new Russian" became the subject of education and nobody knew it before there can't be any dialects for the "new Russian". As a result, today we have a huge territory with the people speaking in the only Russian dialect.