This is an excellent point that I'm amazed no one has made. It's entirely possible to dress very well but without wearing a suit/blazer/wool pants, etc. There are tasteful, well tailored, yet casual clothes all over the place.
That's rather judgmental of you... I thought the whole point being driven by every crunchy, sandals-wearing startupmeister here was that clothes don't matter. How bigoted to immediately dismiss someone for dressing differently.
It's really just a tool like your editor. I personally dress for expedience. There are some forums where i have to go to where power dressing really does have a positive outcome. There are some places (eg. code sprints) where a T-shirt and an old pair of jeans works better.
A slob in a suit is still a slob.