That answer is likely to satisfy the customer and they are more likely to purchase a product from that company again.
That reasoning always sounds good, but again, it comes down to numbers. Real measurable business metrics, and calculating ROI.
What percentage of unit sales come from customers who:
1. Had that 'favorable' customer support experience in the past
2. Purchased this unit directly as a result of #1
3. Wouldn't have made this purchase had #1 not occurred
I'd say that number is pretty low. Or at least, low enough to justify not having an documentation team on staff to create, update, print, and stock your literature inventory, etc etc etc.
Moral of the story:
Unless you have a customer that just has a god-awful, nightmare of a customer support issue, most people aren't going to swear off a brand for something like that. Likewise, something as simple as this won't normally influence the purchase of something they wouldn't have needed/wanted/purchased otherwise (considering the item is in the hundreds of dollars). The majority of consumers make a purchase primarily because its a product they want.
Real life example. OP, are you saying you'll never purchase a Taurus ever again as a result of this issue? If they had printed a manual and mailed it to you, would it directly influence another firearm purchase that you wouldn't have made otherwise? There's your answer right there. I'm guessing if they come out with another product you like, you'll buy it, otherwise, you won't. And just think, you're one of the vocal minority of customers who will actually take the time to go to an online forum to post a complaint...