None of these companies decided one day to write the Spring Framework for Python (or the Rails). We got Django that seems stuck in 2005-2009... (no offense to Django devs).
Python runtime hasn't changed much...
Meanwhile in NodeJS land: - GoDaddy decided to re-write stuff using NodeJS - eBay adopting NodeJS in increasing pace - Progress (.com), legacy software company acquired modulus.io (NodeJS shop) - IBM z Systems supports NodeJS - Go to Microsoft Learning, you'll find lots of JavaScript tutorials (NodeJS or WinJS or Angular)
These companies promote NodeJS up-front. When Microsoft decided to hire people behind IronRuby and IronPython, I thought they decided to adopt those languages but that didn't last long before they cut them loose...