Good question! I believe it's worth it to update the doc. Let me relay your request to doc writers. The correct order is
streamslice(X, Y, U, V, density, 'arrowsmode', 'method')
You can get helped with the "tips" from MATLAB editor like below. (Below is from R2024a)
You can also see the correct order of input arguments according to the order of descriptions of them in the doc. Does this make sense to you?