Shareholders are not insiders. Public companies do secret projects all the time of which shareholders know absolutely nothing about and may never learn the details of them if they get cancelled.
No youre missing the point of the poster - disclosures in private markets are different than public, especially in the context of large commitments - the company has no choice.
The implications are very different if everyone owns them even if they aren’t public. They may have no choice whether to share, but the owners which have the privilege to know (not everyone because earlier owners aren’t stupid) don’t act the same, right?
And let’s be honest - rules get bent all the time, especially when valuations are 9 figures. Stakeholders at this point won’t risk killing a golden goose.
