Because Windows is 30% of all computer installs and 75% of all desktop installs. It has also been the traditional platform of gamers for the last 30 years because the IBM-compatible systems allowed you to install any part you wanted which means it was easier and cheaper to add a high-end graphics card (and in the distant history, a sound card) for gaming versus paying stupid money for a whole “gaming” system at Apple markups. Since that’s where the gamers are, that’s what the games get made for, and that’s what most of the tools are made for. There’s just a LOT of momentum there.
