Your last paragraph has a lot of words but says very little. Can it not all be summed up as "talk to your customers?" Isn't this the foundation of any business? Does anyone actually advocate not doing so?
Obviously you need to be aware of the problems your customers face as a business.
But the notion that anything is the "most important" metric of progress reeks of classic silver-bulletism that plagues software engineering.
I also am not a big believer in "validation." You're never going to "validate" your ideas through customers. You're going to evolve your ideas through seeing people use what you build. But they're never "validated" or "proven right" through intimate customer feedback. Good ideas are "validated" over the course of years, often after much ridicule, resistance, and pain.
"Can it not all be summed up as 'talk to your customers?' Isn't this the foundation of any business? Does anyone actually advocate not doing so?"
I don't think anyone advocates not talking to your customers, but Steve Blank makes a bigger point than that.
The point isn't just to talk to your customers. It's that the CEO, the founders, the people with the control have to talk to the customers.
A lot of companies have the CEO, the programming team, and the rest of the decision makers relatively isolated from the customers, whereas the sales team is the one out there talking to customers every day.
This isolation still makes it look like the company is talking to customers (they have sales out there, every day, listening to customer feedback). But because the real decision makers aren't themselves experiencing the way the customers use their product, they'll never understand it the way they need to to keep making their product better.
'Talk to you customers' is a bi ambiguoud, and could be wrong. My reading of the lean startup thing is that you look at the numbers and metrics of what your customers are doing, rather than ask them what they want. If you're not sure what feature to add, don't ask people, and do surveys, do a half version of all the possibilities, and see what features your customers are using.
Well, 'talk to your customers' is a little different from 'listen to your customers and make sure you understand exactly what problem your product/service solves for them'. And I think the only difference between evolution (as you've described it) and validation is that seeing how people use what you build, and getting qualitative data on those users is emphasised, rather than something that just happens over time.
At a minor level, that could be making sure that the next feature you implement is the one that will make your software much more usable from their point of view, rather than the shiniest or most technically interesting to implement. (e.g. it doesn't matter if your mousetrap automatically telling your computer when it's caught something, if their local mice just aren't interested in $bait_that_works_best_in_bobs_house )
On the larger scale, if your customers are using your product to solve a problem you didn't expect, you can't optimise your product so it sells even better. If the largest user of your mousetrap is the gremlin-catcher's guild, then perhaps you need to look at building more gremlin-specific features, and changing your marketing a little.
And, of course, the simplest metric for validation is that if they ain't buying it then it ain't doing what they want enough for them to pay for it.
Disclaimer: I have never run a startup, let alone used these principles. They just seem to make sense to me.
Obviously you need to be aware of the problems your customers face as a business.
But the notion that anything is the "most important" metric of progress reeks of classic silver-bulletism that plagues software engineering.
I also am not a big believer in "validation." You're never going to "validate" your ideas through customers. You're going to evolve your ideas through seeing people use what you build. But they're never "validated" or "proven right" through intimate customer feedback. Good ideas are "validated" over the course of years, often after much ridicule, resistance, and pain.