Yes, I should have been clearer that it's not that you can't make it on credit, but you can't use it as collateral. Firms usually buy capital, they don't build it with their own hands; this both means different financial instruments are available to them, and they can liquidate that capital.
(But as I said, my comment is kind of made up)
And... if you have to write down an intangible asset you can... and that will reduce taxes accordingly. You can also get loans for intangible assets, use them as collateral, etc. I don't understand what you're saying about not producing software on credit-- of course you can produce it on credit like anything else. You can hire out a firm. Even if you hire a w2 dev you typically have 2 weeks to pay them for work done.