I always wonder, why are they drawn for divergent view? (right plot: right eye, left plot, left eye). Convergent view (cross-eye) is much easier for large (full screen plots).
Swapping both plots, (most) humans can easily see the stereoscopic picture without any aids, but it's more or less impossible for almost anyone to have a 3D divergent view for 3D plots where the eyes look away (wider angle than parallel).
So the size limit for divergent view is _much_ smaller than for cross-eyed view.
It is always great to see 3D plots in actual 3D, while regularly working on a notebook, and convergent view would make that quick and easy...
I used to use them, but stopped once I exceeded the free usage limit.
It was free to use on your personal computer, but I wanted to post the plots on my blog. Also, at the time, using them in the notebook had the same effect as posting it on a blog (in terms of their usage limits). I ran out just playing with Plotly.
I think they should make it free for non-commercial use...