Silicon Alley Insider: The second major threat, however, comes from a company that Microsoft once left on the edge of death: Apple (In fact, Microsoft actually helped save Apple once, by becoming a shareholder, so it could demonstrate to regulators that it did, in fact, have a competitor. At the time, it didn’t).
Editorial; At the time we were confused, it really did not make sense. Later, Apple had QuickTime, and MS wanted it. Apple caught MS incorporating it in media player. That is why MS made a $150 million investment. MS could have calculated that it was in their best interest to maintain a “competitor”, but I wager their best interest was to avoid embarrassment.