I saw the video about Oksana Skorik a while ago on YouTube also, and it did raise some interesting points, and as you have asked for opinions, I would like to offer mine.
I have seen Oksana Skorik perform in many of her roles, and she has clearly been working through some underlying weaknesses in her technique. The ballones performed in the variation in Act 1 of Giselle are an iconic feature of the ballet, and performed correctly by every ballerina in the Mariinsky, as expected by the paying public today. Of course every ballerina makes an occasional mistake, but a whole misperformed diagonale such as this was unprecedented. I saw her Lilac Fairy, Odette-Odile and her Chopiniana also, and there were many technical mistakes apparent here too - notably in Italian fouettes and pirouettes - which showed at the time of performance she also had problems with turns. I did not like her use of her upper body and arms either, whch in my opinion lacked the fluidity and expressiveness of a Vaganova trained ballerina. It is an unfortunate fact that ballet is a tough profession and to turn a blind eye to faults and accept less than the best will only result in a general lowering of standards. Not only that, the paying public is entitled to a certain standard of performance and in my opinion, it was lacking in the performances I saw. Of course, every young ballerina makes mistakes and should be encouraged, but sometimes coaches and management are guilty of pushing a dancer before she is ready to progress. It was unfortunate for Oksana Skorik that she was given roles before she was ready for them and in this respect I am sorry for her: I believe that young ballerinas should remain in the corps until they are able to perform to the standards expected at the Mariinsky. This is only kind to the ballerinas themselves, fair to their peer group and respectful of the audience.
In my opinion the Mariinsky is the greatest ballet company in the world, with a wonderful tradition of Vaganova training behind it and the great ballerina roles in Giselle, Swan Lake and Sleeping Beauty, to name just a few, have been performed by a remarkable series of illustrious predecessors. Every ballerina who performs these roles carries the torch and should be worthy, technically and artistically. Every ballerina in the Mariinsky knows that. Every person who loves the Mariinsky ballet knows it also and wants only the best for this great company. It is just unfortunate that sometimes the desire for these high standards to be maintained may result in some apparently severe criticisms.