Note that the author says that this was "the previous practice". There is no mention of this being, say, the sole intended use as mentioned in some bylaws. In fact, if "uncovering of new information" was the sole reason, why not have a confirmation vote in the same body after a mandatory cooldown period?

The author even explicitly states that "errors in the process" are another potential reason for the NB's to vote against a proposal, so why focus solely on the "no new information" argument?

Also, keep in mind that the WG21 operates primarily by consensus[0], which is explicitly not a majority vote. The final vote for Contracts was 114 in favor, 12 opposed, 3 abstaining, which some consider "an unusual level of opposition" with "tangible debate"[1].

I assume the default is for people to trust that the domain experts in the various subcommittees did their work properly, so an in-favor vote would be more a "I trust the subcommittee / I don't care about this feature" than an explicit "I approve of this feature", with an opposing vote basically being "the subcommittee is making a grave error, this is obviously going to blow up in our faces".

Extend this to the NB level, and the disapproval is basically a vote of "Wait, do we really want to standardize something which is still facing very serious opposition?"

[0]: https://isocpp.org/std/standing-documents/sd-4-wg21-practice...

[1]: https://componentsprogramming.com/cpp26-croydon-wg21-meeting...