I think you've misunderstood the analogy.
He's claiming that without knowledge of the prior state of their systems and the differences (besides implementation language) between the Node.js and earlier implementation that underlies the benchmark, "using Node.js" may be analogous to the orange color in the cheese -- something that came along with the cause of the improvement that is not actually the source of the improvement -- and that splashing Node.js on other applications (as in PayPal's stated decision based on the result of this upgrade to use Node.js on all future consumer-facing applications, but more importantly other people using PayPal's experience to justify using Node.js for their applications) may be analogous to dyeing the cheese.
> They had a measurable increase in success - they made better cheese.
Right. He's saying that "PayPal made a faster web app. They used Node.js. Therefore, we should use Node.js if we want our web apps to go faster" may be analogous to "Farmer Bob's cheese is better tasting. His cheese is orange. Therefore we should buy orange cheese if we want better tasting."
Though, really, like most uses of colorful analogies to get points across in technical articles it does a lot more to obscure the point than to illustrate it.
The TL,DR: You are taking a significant risk of serious error when you accept a claim that a change that preceded an effect caused that effect when you don't know what other changes occurred at the same time that may be relevant to the effect under consideration.
There are two blog posts here, both interesting, but not deeply connected. One is about false proxies, which is specifically about people manipulating perceptions.
The other is about getting "measurably better cheese" but not understanding why it's measurably better. Speed is not a proxy for speed, it's just speed. The meme here is that correlation does not equal causation.
The worst version of the trap is when one manipulates a proxy and honestly believes that they are helping.
[1] http://search.dilbert.com/comic/10%20Dollars%20Bug%20Fix
We benchmark our two important loads whenever we're buying new servers. Surprisingly, some machines perform significantly better on one load, and others perform better on the other. To us, it's non-obvious why that would be so, given what we know about the software running (this software is not written by us, ours falls in the 20% bin).
In any case, this very simplistic try-the-actual-load benchmarking serves us very well.
So when they say they changed to node and things got better, I just take it as, OMG, paypal tried to improved something and it improved.
Im sure it has nothing to do with node.
