I interpreted the original article that their new node.js approach was wildly different than a server-based MVC framework.
Sure, they ended up with 20x greater speed, but never did they say that it was because node.js. They even provide a high-level detailed description of all the things they did with their new approach to achieve this performance.
"LinkedIn Moved from Rails to Node: 27 Servers Cut and Up to 20x Faster" should say something like "LinkedIn did a rewrite and rearchitecture that cut 27 Servers and increase speed aby 20x"
Sure, they ended up with 20x greater speed, but never did they say that it was because node.js. They even provide a high-level detailed description of all the things they did with their new approach to achieve this performance.