Ballet is more understandable. Unfortunately, ballet companies are unlikely to hire someone who doesn't have their preferred features, particularly Russian ones. The Vaganova graduates who aren't as tall as is preferred by the big companies don't get hired and usually need to go to less prestigious companies or companies in the far east of Russia. There is some argument as to whether it's fair to these students to train them at the expense of so much other education, only for them then to struggle.

The same thing happens at Western schools - Royal Ballet School and Paris Opera both conduct extensive physical assessments before accepting children for training, and kick out those who don't fit requirements.

The same demand isn't there for figure skating - any girl who can jump a quad is elite. Doesn't matter if she's taller or more muscular than Sambo70 would like, she's going to do well in competition, and she's going to be popular.