Yeah, this is more of a Microsoft using its monopoly for years to push game development towards a more Windows locked in direction. Had games been built on open standards MS would have lost its PC game market ages ago, and the Xbox wouldn't have had its impact on gaming the same either early on. Making every "PC" game run on DirectX and making calls to Windows DLLs made those early Windows to Xbox ports easier and helped MS leverage the monopoly into another market more easily. Wine and now Proton have come a long way, but needing to reverse engineer things all the way through is a lot more work than just implementing a standard would have been.