Am I wrong that in that article magma appears to do better? Particularly in the last two (red-blind and grayscale), it seems like viridis looks the same for large parts of the scale, while magma retains its distinction.
I think it just won the poll [1] because it subjectively looks nicer. NJS, in that video, said something like: I don't care which wins, they're all so much better than the current situation. But magma is a good choice too and it's also available in matplotlib.
[1] http://bids.github.io/colormap/