I object to the idea that this is a gesture. These are people pledging their reputations to quit their jobs if their employers don't prevent the data they collect from being abused. It's not just possible but likely that people will quit jobs in the next couple years because of this.
The objection that the pledge doesn't solve the problem is easy to make because it's true: the pledge alone won't solve anything. But make no mistake: this isn't a petition. Whether 10 people or 1,000,000 people sign a petition, the effort fails if the target ignores it. But a single person can sign a pledge and, in honoring their commitment, do something significant in support of their cause. It's not up to the employers; it's about the workers.
I think this kind of bottom-up effort is both promising and overdue. More people should consider signing. What's the threshold we'd need to reach in our profession for a pledge like this to meaningfully impact decisionmaking? I think it's much less than 51%.