Well, it's a comparison of different ruby versions, using Rails. That's pretty useful to people who use Rails, which is a lot of people.
Of course, it's not a real Rails app presumably, but just a sample/dummy one. So you may or may not see comparable speed-up with a real app. But it's probably suggestive of the upper limit of improvement you can get by switching ruby versions.
"Will I get a performance improvement from my Rails app by upgrading ruby" is a real question a lot of people will have. Micro-benchmarks of ruby wouldn't answer it as well as the OP does.
