It is not necessarily bad if people hired cannot make it through. Reasons:
1. Standards got higher. Luckily if you got in early and proved yourself you are OK. But doesn't mean you would pass the current interview.
2. A marathon runner (with rare exceptions) can't run a marathon on a random day. They train for a specific date. Same with interview prep.
If I read the article correctly, they handed the hiring committee /their own/ anonymized packets and the committee chose to only hire 1/3 of themselves. That mean numer 2 is not the case. Presumably the hiring committee prepared for their interviews of they passed their rounds.
Number 1 can still be true, and likely is. But then what's the point of using dated packets to test the hiring committees calibration?