Which only matters when it matters. There's lots of use in having sometging hackable. And who knows where it's heading. So no need for the "it's not as scalable as X hence it's worthless" attitude...
Another thing, the fact that you're blocking JS may counter the "you're running it" example, but as you know, it doesn't invalidate the point that JS in one of the most used languages.
And X is way more fast/scalable/mature/secure than Twisted and Event Machine for some values of X I'm sure, yet Twisted and Event Machine are still worthwhile and useful things.