In case people didn't read the blog post before coming to the comment section, the blog is actually defending Meteor as a new framework that might be worth observing.
I feel the same way about OP. Rails is awesome, but Meteor really excels at some things Rails lags behind in. Data binding between database and browser asynchronously which is doable in Rails but it is pain in the ass. Rails simply wasn't made for this kind of app. Times have changed and user are demanding different kind of UX for some apps. I am glad that there are new tools like Meteor in development to fulfill these roles.
I think that much of the reaction in the original post comes from the overly-bombastic headline: "Why meteor will kill Ruby on Rails". If it was sold as "Meteor.js: an exciting new technology for building real-time webapps", I could get behind that, because building real-time websites is currently hard and Meteor makes it easy (easier?). But if you say Meteor is going to kill Rails, you are positioning Rails as Meteor's competition: and when I look at what Rails is used for (quickly building multi-page DB-backed sites with relatively small levels of interactivity), Meteor sucks at that job. There's little reason to use it, and a lot of reason not to.
Hype and blind optimism kills promising new technologies far more often than competitors do. Picking your competitors carefully is important. If you position Meteor against Backbone or Angular, you might have a case, and then we could evaluate based on the technical merits. But if you position it against Rails, they're built for completely different use-cases, and so of course Meteor is going to fall down.
I feel the same way about OP. Rails is awesome, but Meteor really excels at some things Rails lags behind in. Data binding between database and browser asynchronously which is doable in Rails but it is pain in the ass. Rails simply wasn't made for this kind of app. Times have changed and user are demanding different kind of UX for some apps. I am glad that there are new tools like Meteor in development to fulfill these roles.