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.
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.
I also agree that for collaborative open source projects a different approach is often preferable (as well as governments too obviously).
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.
Because it's a tax write-off and makes for good press?