The reason I ask is because there are so many different graphics APIs, of which Vulkan is the one that has the lowest rates of direct targeting.
You’re looking at custom platform APIs everywhere but Linux. Windows and Xbox only officially supports DirectX (including console variants here), PlayStation have their own, Switch supports their own plus Vulkan (and most people don’t target Vulkan on there).
Even Metal has significantly more games targeting it due to iOS support. Before people say those are only mobile games, thats a severe underestimation of what games are on mobile.
So every cross platform game needs to support multiple APIs anyway, and even if you count every API , Vulkan is by far in last place.
Edit: I’ll also add that both macOS and Linux had lack of games when their only API was a cross platform one: OpenGL. yes, macs GL is outdated today but it wasn’t always , and just like Vulkan, very few games directly targeted GL anyway.