It's completely wrong logic. It's not about demography. It would be so, if in every small town there would be conditions such as in Moscow. But it's not.
Figure skating is an expensive sport. Ice time rent, skates, dresses, etc. Skater parents (usually mom) should be really involved, so again it requires some prosperity. For example, Nastya Zinina (silver medal on show "Ice age. Kids") came from Rostov together with her mother who lives with her in Moscow. But this means that their dad can afford to keep them in Moscow. Believe me, not every russian family has such incomes. Heck, many can not just rent an apartment in Moscow as did Zagitova's family.
But this is only one side of the problem. Our sports infrastructure is not sufficiently developed. The first thing about which Zhenya asked the president when team met with him - new skating rink. She
spoke about this at the press-conference. Then Bobrova said that she had the same request to Putin (Katya and Dima simply did not have own ice rink). Then Eteri Georgievna explained Zhenya's words that the team boys were beating their heads against the ceiling - old basements were converted into new training halls. And explained that in the Сrystal normal situation with the ice for athlets, but by reducing the time for young children : "
I'm completely realized this, I walk along the corridors and I'm ashamed to look into the eyes of the parents of small children, cause they don't have the opportunity to skate". And it's about Moscow, in provincial cities, the amount of ice is very limited.
But most importantly - specialists. TAT every time (even on "Ice age") said that there are not enough trainers, that it is a difficult job, that is not paid very well. So trainers are a resource too. And a limited resource, also concentrated in capitals (Moscow, Piter).
So, no - it's not about demography. It is a complex mixture of economic opportunities and inner passion and willingness to endure difficulties. Sorry, i was slightly chaotic, but I hope you understand me