Sole? No. No matter how many times people repeat it. Or, at least, companies can and do spend money on things that can be argued to be in service of the long-term profit and image of the company. Otherwise, how could a company do charitable giving?
That said, if someone makes an offer for a public company, the board does pretty much need to put it to a shareholder vote although they can negotiate for a higher price and ultimately make a recommendation. But it's up to the shareholders. They're the ones that own the company.
This is why I'm in favor of founder controlled shares (Founder's Fund companies tend to do this - Zuckerberg at FB).
Founder's retain total voting control of the company and can do what they think is in the best interest of the company.
The board can complain and vote against it in favor of stupid short-term decisions that harm in the company, but in the end Zuck can tell them to fuck off and buy instagram because he thinks it's the right thing to do.
While I don't completely disagree, a Benevolent (or not) Dictator For Life can have it's own set of problems. And I'd not that it's generally not considered a great governance model for large open source projects--though that's obviously a somewhat different situation.
I agree founder led companies are more like dictatorships (though feudal earldoms may be a better analogy?), this becomes less true in older companies no longer lead by a founder. I agree there’s risk (founder could lose touch or go crazy), but I think that risk is less likely than bad board decisions by non-founders. It’s also bounded a bit by the ability to retain high quality talent.
I also agree that for collaborative open source projects a different approach is often preferable (as well as governments too obviously).
> And I'd [note?] that it's generally not considered a great governance model for large open source projects
Citation needed? Offhand, it's worked great for linux, and while perl and python have had some infamous problems, they don't seem particularly specific to the BDFL model, and they seemed to work well before that.
"long-term profit" is the long-term financial returns to shareholders -- and corporate philanthropy is generally held to be justified in B-school circles only in so far as it builds up marketable goodwill (again, adding shareholder value), not for its own sake.
This is why some companies and interests are better off staying private. SpaceX is a perfect example. Musk doesn't want to be accountable to shareholders for return on investment and annual results.
At that point though, just about any reasonable actions can be justified even if they're not in the interests of immediate quarter earnings per share. And that's not what most people arguing that the board is legally required to maximize profits are talking about.
That said, if someone makes an offer for a public company, the board does pretty much need to put it to a shareholder vote although they can negotiate for a higher price and ultimately make a recommendation. But it's up to the shareholders. They're the ones that own the company.