Hmm, I see a pretty clear decline in her jumps from 2015 Worlds to 2018 Olympics.
That being said, I'm just going by what Zhenya says. And she knows her own body well. Even Eteri says that the secret to her skaters' success is the hard training regime and multiple runthroughs. It's not hard to see that that wears you down when you no longer have the right body for it or the youth to bounce back from injuries. Do you think the reason behind the men's inconsistency is that they're not doing enough runthroughs? Sounds like a joke.
Zhenya, as an Olympic silver medalist and 2x World Champion, probably doesn't care that much about another World medal as much as she does to go to the next Olympics. The probability of that is probably close to 0% with Eteri. Even if it's 5% with Orser, it's a rational and very mature decision for her. She is smart to see the forest for the trees.