However, in practice, it is what matters, There is a "minimum" threshold (I can attest to this because I've been on the other side having to conduct them) where you more or less, must finish at least with some viable answer - even if unrefined - or you won't be moving on, full stop
Interviews are very different from working together collaboratively. They're very different from presenting work to or working with a client or stakeholder, too, and even very different from a sales presentation. The space of things that might come up is effectively unbound, how you're being judged is wildly uncertain, you are being judged, and you know almost nothing about the people you're "working with". As practiced in software, they're closer to being called in to give a thesis defense without knowing in advance which thesis you'll be defending—and also everyone in the room is a stranger, and also you have no clue which aspects of your performance are being judged or by what criteria, and even know for a fact that some of the people conducting these have completely opposite opinions about which behaviors are desirable and which are "red flags".