The threat of professional exclusion is one of the big levers provided by such a guild. Given the way tech companies behave, why do you believe that this lever will be left in the hands of good people, and not taken over (like the rest of the internet)?
I think there are more developers opposed to the recent web attestation shenanigans than those for it (even those who might be coerced into being for it by their employer). A majority guild vote could stop everyone working on it and keep the web open.
Yes, and if you can hold and retain power over the guild then the power of professional exclusion exceeds the coercive power of any one employer. But when your threat model includes adversaries who are willing to subvert the entire open internet to get their way, how do you harden your guild against this attack?
The threat of professional exclusion is one of the big levers provided by such a guild. Given the way tech companies behave, why do you believe that this lever will be left in the hands of good people, and not taken over (like the rest of the internet)?