By "OP", are you referring to the author of the blog post, Charles Nutter? It doesn't seem like an easy feat to not understand Ruby when you've written a major implementation of it, namely jruby in this case.

It's also pretty hard to spend a very significant amount of your time implementing a language you don't like. Finally, addressing his use of Ruby: https://github.com/headius

Your logical fallacy is ad hominem or appeal to authority. It doesn't matter who he is or what he has built.

The poster seems to favor a more complicated interface with a simpler implementation. That is basically the opposite of what is great about ruby: a simple interface with more complex implementation.

You want a run-down of couple points, fine. These exemplify the misunderstanding of the goal of Ruby.

> Fixnum to Bignum promotion

The entire point of class promotion is to remove the constraints of Java, C, et al. have to the machine architecture. And then there's the transparent and dynamic treatment of variables. Class promotion and dynamic typing allow a more math-like syntax and usability.

> Closures

It is entirely freeing to have blocks treated as they are. Java is no comparison, its overly verbose syntax and lack of dynamic variable scoping is supremely limiting. Similarly, it is a question of brevity, least surprise, transparency, and dynamism.