Aras is right, but the elephant in the room is still shitty mobile GPUs.
Most of those new and fancy techniques don't work on mobile GPUs, and probably won't for the foreseeable future (Vulkan should actually have been two APIs: one for desktop GPUs, and one for mobile GPUs - and those new extensions are doing exactly that - splitting Vulkan into two more or less separate APIs, one that sucks (for mobile GPUs) and one that's pretty decent (but only works on desktop GPUs).
WebGPU cannot afford such a split. It must work equally well on desktop and mobile from the same code base (with mobile being actually much more important than desktop).
Most of those new and fancy techniques don't work on mobile GPUs, and probably won't for the foreseeable future (Vulkan should actually have been two APIs: one for desktop GPUs, and one for mobile GPUs - and those new extensions are doing exactly that - splitting Vulkan into two more or less separate APIs, one that sucks (for mobile GPUs) and one that's pretty decent (but only works on desktop GPUs).
WebGPU cannot afford such a split. It must work equally well on desktop and mobile from the same code base (with mobile being actually much more important than desktop).