Growth rate is not an excuse for the evils that have been enabled by Facebook. It is perfectly within Facebook's power to slow its growth to a rate it can actually manage.
And don't play the "shareholder" card. Zuck is the majority shareholder, and can do whatever he wants with the company, including making it not be evil.
Is there another app that, indeed, connects the world?
E-mail. The PSTN. Text messages. Actual mail.
WhatsApp, YouTube, and probably several hundred others that I don't know about because I'm not much of an SMS person.