I think I could write a scalable Twitter using mostly low-paid workers who manually write down the tweets and deliver them in person. It's just a matter of hiring enough workers now that I've designed this scalable distributed system.
Compared to the OP, your post is just random, non-funny sarcasm. The OP has highlighted relevant data points.
1. Writing a system the second time is easier since you already know the pitfalls and avoid them.
2. Ruby, Python, Perl, Java... provide thin wrappers for the underlying IO system calls, and hence, Java IO isn't very different from Ruby IO when it comes to performance.
3. There are only a few CPU intensive tasks. It goes without saying that Java will kick Ruby's(pure Ruby; native extensions will be a different story)ass when it comes to CPU intensive tasks.
Computers are easier (though perhaps less fun) to make than humans. Ruby is slow but it's close enough to Java that the numbers will still work out. Humans: probably not.
