https://redmondmag.com/articles/2014/04/28/court-nixes-novel...

The case brought to light an Oct. 3, 1994 memo from then-Microsoft CEO Bill Gates, who indicated that Microsoft should withhold namespace extension APIs in Windows 95 from its competitors, WordPerfect and IBM, in order to gain market advantage for Microsoft Word.

In other words, your revisionist history is wrong. Microsoft really was big enough. We know that because WordPerfect asked for early access to Windows 95. It was Microsoft who turned them down. (And no, I don't believe Gate's testimony about security. I think that Gates was bamboozling the judge, and the judge bought it.)

(I had misremembered which court case brought that memo to light. But regardless, it was obvious to the whole industry at the time. Incidentally this memo came while Microsoft was under a consent decree signed on July 25, 1994 with the Justice Department to not try to maintain their monopoly by tying specific products to Windows. Technically, they didn't here, but they were walking the line. They crossed the line with IE though, and that later resulted in the Netscape loss.)

As for BeOS, the question was how a LEADING operating system company was supposed to cope with getting software for the next version of their OS. No matter how many good things we can say about BeOS, they never got to the point of being a leading operating system company.