And in fact, a viable competitor alone is often enough to stop abusive behavior from the market leader. If the market leader knows that they will quickly use ma

And in fact, a viable competitor alone is often enough to stop abusive behavior from the market leader. If the market leader knows that they will quickly use market share if they start abusing the users, they will not abuse the users. So a competitor like Linux or Firefox is helpful even if market share never gets very high.