Fiduciary duty absolutely does go beyond accurate communication and fraud. Directors have a duty of care that goes beyond simply not engaging in criminal fraud. Sure, you don't have to be competent, successful, etc. It is completely legal to suck at your directorship. But it's not legal to do something that you can't justify as being good for the business, which is where a public benefit activities can cross the line.

Consider the eBay/Craigslist case, eBay Domestic Holdings v. Newmark:

> When director decisions are reviewed under the business judgment rule, this Court will not question rational judgments about how promoting non-stockholder interests—be it through making a charitable contribution, paying employees higher salaries and benefits, or more general norms like promoting a particular corporate culture—ultimately promote stockholder value. Under the Unocal standard, however, the directors must act within the range of reasonableness. Ultimately, defendants failed to prove that craigslist possesses a palpable, distinctive, and advantageous culture that sufficiently promotes stockholder value to support the indefinite implementation of a poison pill. Jim and Craig did not make any serious attempt to prove that the craigslist culture, which rejects any attempt to further monetize its services, translates into increased profitability for stockholders.

https://courts.delaware.gov/Opinions/Download.aspx?id=143440

This is where a PBC would have been different. With a PBC, courts are directed to balance the the stockholders interests with the company's stated public benefit.