Code Optimizers Can Make View Source Useless
What’s different from some tools in other languages (like ActionScript obsfucation tools) is that Closure and others of its ilk aren’t primarily designed to obfuscate, they’re simply optimizing code, making it smaller and faster. As Russell writes, “the Closure Compiler can deliver code that’s much, much smaller than I can wring out by hand and that performs better to boot.”
As Russell writes in a followup comment, “poll any average group of web developers and they’ll tell you straight-up that that’s how they learned… not be stealing, but by dissecting and inspecting and tweaking and then re-implementing a technique in a new and unique situation.”
Tools like Closure make the source you view of little use. True there are some “de-obfuscation” tools out there — like jsbeautifier.org — but none of them work with tools as sophisticated as Closure.