An extremely good interface for editing and retouching photographs
Okay for doing painting and bitmap art creation
Mediocre for doing graphic design -- alignment and layout are frustrating
Abysmal for doing web design that isn't brochure-like
Omnigraffle is a terrific example of a general graphic design app that is suitable for web design.
I agree (as much as I can without actually being a designer), and I think a lot of people have lamented the loss of Fireworks when Adobe gobbled up Macromedia. It's also worth mentioning that Inkscape is a good tool if you're on Linux or Windows.
That said, regardless of how mediocre or abysmal Photoshop might be for graphic/web design, it's what most people seem to be using for it these days.
I remember reading this article when it was originally posted last year and thinking that it makes sense for 37S to skip Photoshop mainly because they already have a strongly defined, common visual style for their web apps. I get that the 37S visual style could be seen as "not doing any graphic design" and I assume this is meant in an at least partially facetious way, so don't worry, I get the joke and the serious point contained within it. I am however happy to stand up and say that I am one of those who likes the bare visual style that 37S pioneered.
But none the less, skipping the non-functional mock-up stage does not make so much sense for your average (say, freelance) web designer/developer who is directly servicing multiple clients, each of whom expects a completely different visual style for their website. I remember following a link (somehow connected to this 37S post, maybe in the comments or something) to this post:
As often seems to be the case, some people think that what 37S says works for them should invariably work for everyone else without modification and if it doesn't, then that somehow invalidates any value that their advice may have had. o_0
