You're too close to the forest to see the trees. Forget you are a hacker for a minute and think of yourself as say a screenplay writer. Where would you rather be, LA or some hicksville town ? If you are in LA and you bump into some two-bit actress moonlighting in a bar and talk about your script, soon, she'll connect you to someone who knows someone else who knows something who will soon reshape your unsellable script into something that can actually get made and within a span of a few weeks you'll be on a studio lot while they go over the makeup of a costar you only saw on TV until yesterday! Sounds like complete baloney, but that's how it really works!! You can read say William Goldman's book Adventures in Screen Trade where he spells it out in considerable detail - Why professors with PhD in literature are still working on the nth draft of their dream project in the English Dept at Andover while some street smart dropout hacks away at a script on a couch in some dinghy motel on Hollywood Blvd that actually gets made.
It ain't fair but that's how it is.
In you go to SF with your pet project which has no traction and revenue, it will suddenly have traction and revenue. Don't ask me how. It isn't exactly logical. Things happen. You'll meet people who'll tell you if only you change this feature and add that feature and do this and not that you'll have a saleable proposition. So you'll say what the hell and give it a shot and soon it becomes so! Its just not rational, and as a coder and mathematician I hate irrationality just as much as you. But that's how it is.
Whereas with no such brutal feedback, you can labor away at some precious project until it becomes larger than life and super-brittle and soon even you don't want to touch it cause who knows which module will break which other module, and then you go looking for customers and nobody really wants it cause its gotten way too complex for anybody to decipher.
I've heard ideas that are so lame ( an app that counts ONE TWO THREE while you do pushups. Really! Yeah, that's got funding to the tune of a couple mil! ) your 3 year old could have come up with it. So its not the traction, framework, revenue model etc. Its just finetuning an idea to the point where it becomes saleable. And for whatever reason, perhaps because its in their DNA, SV seems to have the sort of people who actually give you a listen and then tell you exactly how to go about it. They actually give a damn! If you have an idea, I think you should atleast spend 1-2 weeks in SV trying to pitch before writing it off as a futile exercise. Nothing to lose, everything to gain.