I had this complaint myself not long ago, but Vulkan isn't targeted at new computer graphics programmers just learning about the graphics pipeline, or vertex and fragment shaders. It's certainly not optimised for the 'hello triangle' use case—your complaint is equivalent to someone saying 'why do I need #include <cstdio>, and a main() just to print "hello world"?' A lot of that boilerplate is write-once, meaning it's first-time setup that will never have to be done again after actually initialising the GPU. You'll find that extending that example to include texture mapping, mipmapping, supersampling, and even GPU compute will be a lot easier than the initial code.

Vulkan is targeted at graphics and game engine developers who want to extract the maximum possible performance from their GPUs and know the limitations of a global-state API like OpenGL. Vulkan allows extremely fine-grained pipeline management and synchronisation primitives, and adds in hardware ray-tracing support natively without having to uncannily bolt it on.

If all you want is to draw a three-coloured triangle, you can do that easier and faster with ShaderToy instead of fudging with Vulkan. If you want to write a fast, powerful, modern graphics engine, then you use Vulkan or D3D12.

People forget that GPUs are now massive slices of silicon with memory and power subsystems in their own right, and are obviously extremely powerful hardware. At some point, OpenGL itself becomes a bottleneck, or is difficult enough to program with that Vulkan becomes easier, and that's when the true utility and power of its extreme verbosity is displayed.

For the record, the boilerplate isn't '921 lines of nothing'—it's effectively setting the GPU up from scratch, similar to bootstrapping a CPU from 16-bit real mode.