I don't think that's true? The goal of vouch isn't to say "@linus_torvalds is Linus Torvalds" it's to say "@linus_torvalds is a legitimate contributor an not an AI slopper/spammer". It's not vouching for their real world identity, or that they're a good person, or that they'll never add malware to their repositories. It's just vouching for the most basic level of "when this person puts out a PR it's not AI slop".
The problem is at the social level. People will not want to maintain their own vouch/denounce lists because they're lazy. Which means if this takes off, there will be centrally maintained vouchlists. Which, if you've been on the internet for any amount of time, you can instantly imagine will lead to the formation of cliques and vouchlist drama.
Point is: when @lt100, @lt101, … , @lt999 all vouch for something, it’s worthless.