Absolutely! That and being able to run code directly in the context of the page through the dev tools console.
Even these days if i'm having a poke around somebody else's work, one of the first things i do is to pop open the dev tools and start seeing which libraries they're running and what their custom namespaces are.
Even these days if i'm having a poke around somebody else's work, one of the first things i do is to pop open the dev tools and start seeing which libraries they're running and what their custom namespaces are.