The author also says that it's perfectly acceptable for something to be 10x slower, because "a well-capitalized company" can afford 10x more servers... I am thinking of how to respond to that, but I don't know where to start
Here's a suggestion: compare it to using 10x as many programmers to write something in J2EE because it's easier to hire 10 J2EE drones than one RoR whiz (where "whiz" is understood to mean "person who has experience solving RoR problems").
It's all a question of what you believe to be the scarce resource. H=e obviously believes that for a well-founded company, server CPU cycles are not a scarce resource. This implies that he believes that RoR addresses some issue raised by something else being the scarce resource.
There's also the issue of the timescale. Start with one programmer and server. You have the finances to purchase 10 additional servers or hire one additional programmer.
You can get 10 servers bought, delivered, installed and configured in one week. These servers can be deployed to do anything from load balancing, web caching, database caching, being database read slaves or application servers. Regardless of the quality of your architecture, 10 servers will probably add some scalability to your system. Furthermore, they can be re-purposed as the situation demands.
Hiring a better programmer (or just another warm body) takes longer. Furthermore, the improved code they produce isn't as flexible as surplus hardware.
Of course, the situation changes when you've got thousands of servers.
