I've found it kinda weird how Rack isn't emphasized in the Rails tutorials. It's really one of the crown jewels (heh) of the Ruby ecosystem. I suppose Rails wants to abstract away all the nitty gritty request based stuff but it's really powerful if you know how to use it.
You're absolutely right. Rack is incredibly powerful!
Might it be possible that there is a subtle catch in "if you know how to use it"? The more powerful a tool is, the more potent a temptation it can present to those who might understand what Rack can do but who could perhaps also stand to possess a greater degree of wisdom in considering what the right tool is. A small number of very experienced, wise, and deeply skilled developers can be trusted to use their tools well - yet this may not describe all possible scenarios.
Again, you're completely right. Rack is vastly powerful and immensely useful. Yet perhaps there might be good reasons for not quickly introducing people to all the glory and power of Rack.
