That year Anna P's competitors were struggling too. At nationals that year, Alina (a junior at the time) outscored everyone but Evgenia. So they did what they usually did - take the top 3 seniors. Also keep in mind, Anna P. medaled that year, Staysa didn't in 2019. Adelina wasn't even competing in the 2016-2017 season, Yulia struggled all season - withdrawing twice, including at nationals - and never competed again, and Liza finished 8th!! at nationals and finished second to Polina ( a junior at the time) in the Cup Finals. If anyone, could have gone, I think it could be Elena, who medaled at both her GPs (winning one) but she had already lost three times? to Anna P that year - at Rostelecom, GPF, and at nationals. As for Stasya, she was still a junior internationally that season and finished behind Anna P and Elena at nationals.
So this isn't the same scenario. You could have withdrawn Anna P maybe but she had already beaten everyone else who could contest her more than once and they were arguably struggling more than her. Russia didn't quite have the abundance of riches then that it does now or even that controversial year. When you look at the 2019 scenario, you have a reigning Olympic gold medalist from the year before, a reigning Olympic silver medalist from the year before, the newly-crowned European champion, the recent GPF bronze medalist, and fed favourite Staysa. However, while you could argue Adelina and Yulia also had similar Olympic pedigree (with comparably impressive bodies of work at the junior and senior level, particularly junior) both of them had already been struggling for the entire prior season with Adelina never competing at all due to injury in addition the the current season. They were already retiring. Once again you have Liza but for the second year in a row she finished 8th at nationals and in this case she'd been struggling for two years and had already been beaten multiple times the last two years. Elena, you could make a case for. But she had already lost three times to Anna P so that isn't the 1-1 of Evgenia and Liza in 2019. Stasya, as previously mentioned, finished lower than Elena (and Anna P) at nationals. And she was still a junior internationally who didn't even qualify for the JGPF and only finished 6th at junior worlds which would have taken place only 2 weeks before. So unlike the choices for the 2019 world championship where there are 4 skaters (and Alina) who have valid claims to the spots, despite Anna P's struggles she is the clear choice.