Of course the result is what matters. But hypothetically, if you can throw together the basic CRUD of an app in 5 minutes with one toolset, and it takes 2 days in another, which one is more likely to let you hone in on the fine details? If one toolset lets you automate testing really easily, and the other doesn't, which one is going to make you feel freer to experiment and improve?
Yes, tools don't matter. Output matters. But tools affect output. So tools matter.
I'm not saying one should rewrite one's codebase in The New Hotness every 6 months - that would be crazy. Which maybe is the author's point.
Sorry, I probably confused you. I'm strictly referring to the actual HTML/JS output of a Ruby or PHP web application. Sure, production output matters, but my point is actual output doesn't necessitate using a particular language in this case. I believe that's is what the original author was referring to in his original post, especially considering the context.
As for your hypothetical situation, I imagine for those reasons and more, they continue to use PHP. PHP isn't devoid of these tools (and I'm not suggesting you are suggesting that), and they are widely used and fairly popular. And because they are proficient in PHP, they can use these tools easily.
As has been mentioned by the original author (in both the original post and in comments), they don't use PHP as a hammer, and they do explore other languages. Learning is good. Take what you learn, and apply in a language you are extremely proficient at.
Yes, tools don't matter. Output matters. But tools affect output. So tools matter.
I'm not saying one should rewrite one's codebase in The New Hotness every 6 months - that would be crazy. Which maybe is the author's point.