It's the same as when people say that Elon Musk is the founder of Tesla, and most people have never heard of Martin Eberhardt (who I think had another partner who's name I can't remember!).
The other interesting story that I thought went missing was when they talked about Bill and Paul working on the class scheduling software for the school after the all-boys school merged with another school to allow girls in. I think they missed the story about how Bill set up his schedule so that he could be in an all-girls class.
Overall, it was a pretty good documentary. I do want to note that it focuses more on Bill's philantrophic efforts, especially in Episode 1, but then Episodes 2 and 3 do a good job of covering his history and Microsoft (though still more focused on his recent philantrophic work.) So this is just a PSA for anyone more interested in his Microsoft story: you may find that more in Episodes 2 and 3.
There was no mention at all that Microsoft bought it. https://www.windowscentral.com/microsoft-bought-ms-dos-os-ea...
This happens frequently in business and tech. CEOs look like geniuses when they can take credit for the work of others.