A company that neutralizes, buys or destroys competitors can treat its users far worse - invade their privacy, cheap out on moderation and anti-spam, etc - without losing business. That's why Zuck's motto is "it is better to buy than to compete":
Of course, as a leftist, I know better than to count on markets as a reliable source of corporate discipline. Even more important than market discipline is government discipline, in the form of regulation
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