Yes, WebGL requires some of the same tricks needed in the D3D9 era (batching and avoiding redundant state changes).
I'm quite confident that WebGPU will still provide a nice performance boost compared to carefully written WebGL, because the API is a better match to the underlying native APIs (D3D12, Vulkan and Metal), while ANGLE is basically a GLES2/3 "emulator" on top of D3D, and D3D11 is quite different from the GL programming model.
I'm quite confident that WebGPU will still provide a nice performance boost compared to carefully written WebGL, because the API is a better match to the underlying native APIs (D3D12, Vulkan and Metal), while ANGLE is basically a GLES2/3 "emulator" on top of D3D, and D3D11 is quite different from the GL programming model.