You are saying you must be top 3 at nationals, period, which is definitely not the selection criteria. As for Polina, she has a very respectable history, but has not shown herself capable of being competitive this year, and has never medaled at a major international event other than FCC 2+ years ago, before her injury and growth spurt (assuming that even qualifies as a major event, as it rarely includes more than 2 of the top names). If she skates the lights out with new jumps she wasn't ready to include on the GP circuit this season, and other skaters do poorly, that would be reason to reevaluate, but if she just happens to fall in third because no skater is skating their best at nationals, I can't see how that would make her deserving of an Olympic spot.
I think most posters (like me) do not think that any of the ladies have met the selection criteria to allow them to bump another skater if they are outside the top three. Hence, a skater needs a top 3 finish to make the team.
The only skater who has been consistently good is Bradie.
Seriously - how often has that criteria been used? It's been on the books for 20+ years and I think only once for the ladies. Kerrigan got a medical bye years ago which different from the selection criteria being discussed here.