Vulkan for better or worse seems super targeted at AAA gamedevs, here's a probably unfair 1189 line example of how to show a triangle: https://github.com/SaschaWillems/Vulkan/blob/master/examples...

AAA gamedevs (and even C- gamedevs) generally use gaming engines (Unity, Unreal, etc). They don't write direct Vulkan or GL. Practically only the Engine people need to care about Vulkan's complexity.

Besides, while the boilerplate for Hello Triangle is indeed very big, it makes a lot of stuff easier to express on top of it. GL may have a much smaller Hello Triangle, but you have a lot less control over it, way too much stuff happens under the hood. And regardless, if all you want is to animate a web page with fish on an aquarium you really should be using GL instead of Vulkan.

Isn't it just because Metal came before Vulkan?

I suspect that Apple has highly optimized Metal to support their own new processors.