That's true. My post assumed a software-centric view of the world, where costs are very low and all that matters is a great product.
In most other businesses, it would be very important to know how many widgets you need to sell at what price to float the loan payments for production or to know all your overhead costs before taking on a consulting/service contract. Neither of those require long range planning, though, which I think are still guesses. The immediate budget and plan, however, is important.
"we need to push back on the growing belief that they can eschew writing a business plan when they are too busy 'doing'"
How many startups change their business model when they realize something is not working? Most?
I suppose the only valid thing coming from a business plan is the recognition that you're not hitting your goals, you're running out of runway, and you better adjust course.
Other than that, guessing what your revenue will be 3 years from now and how many employees you'll need to satisfy those mythical customers seems to me to be a colossal waste of time when you could be busy "doing."
Big company salary (plus 401k match, stock, bonuses, etc.) in an area that is, from what I read, ~11% cheaper than average.
Life is good.