I think the main positive impact Microsoft had on the tech industry that they don't get enough credit for is that they allowed a competitive market for hardware

I think the main positive impact Microsoft had on the tech industry that they don't get enough credit for is that they allowed a competitive market for hardware to exist. (This was in part because IBM didn't insist that DOS be exclusive to IBM devices.) Hardware wasn't their business, so from their point of view, the more suppliers the better. We had fierce competition between manufacturers and they /mostly/ competed on a level playing field (with some notable exceptions that involved antitrust lawsuits). Eventually the hardware free-for-all created an environment where Linux could also flourish which has undermined Windows to an extent. At this point Apple has a structural advantage over Microsoft in that Apple doesn't need to monetize their operating system to be profitable, as they're funded by hardware sales. That frees them up to provide a better user experience because they don't have to find way to make money off of their users. Not many companies are in a similar position, where they can recover software development expenses solely through hardware sales. There are a handful that could in theory, but they seem to lack the willingness.