Because Microsoft supports critical applications that businesses use for well over ten years in a lot of cases. Zero other operating systems have to provide the platform stability that Microsoft does.
So, of course, if they have to focus on supporting only one, archaic platform, they never move forward or create anything new or improved. Which doesn't make sense. So you continue to create newer, better platforms, but continue to support the old ones for years to come. Eventually, older ones fall out of use and can eventually be retired.
So, of course, if they have to focus on supporting only one, archaic platform, they never move forward or create anything new or improved. Which doesn't make sense. So you continue to create newer, better platforms, but continue to support the old ones for years to come. Eventually, older ones fall out of use and can eventually be retired.