Crap. Sorry for the wrong link! My score will probably go to negative now :| http://symmetrycode.com/workflow-designing-websites-browser/
The author got quite a bit of flak in that Reddit post, some suggesting that he must just suck at Photoshop and took the easy way out. Or that thinking immediately about how the design will work in the browser is too constraining.
But what you see is that most of the replies are framed in the context of delivering websites to clients, perhaps of the brochure/pure-informational type. But where you hear a lot of the success stories of in-browser design is from those working on web products for the long haul. Where you don’t have to perform a circlejerk with a client to release something in the wild and need to “design within the constraints of the browser” to ensure the UI is a palatable and useful tool and not just merely a pretty face.
So if you fit in the camp above, in-browser design is totally a viable solution to the typical Adobe stack, and can save you time and headaches if you’re in the right situation.