To better visualize how middleware can lock projects to specific platforms, one can generally create a flowchart of supported targets. A very prominent example being 3D rendering APIs and the battle that has been playing out to capture developer share. When looking at the following graph, ask yourself which starting point (red nodes) is going to offer the widest interoperability.
Any developer building their project atop DirectX or any DirectX reliant tools is effectively placing their software on a ball and chain to Window$.