> Why didn't they? Hint: it's not because it would have taken them longer without AI.

Yes it is. "How much will this cost us to build" is a key component of the build-vs-buy decision. If you build it yourself, you get something tailored to your needs; however, it also costs money to make & maintain.

If the cost of making & maintaining software went down, we'd see people choosing more frequently to build rather than buy. Are we seeing this? If not, then the price of producing reliable, production-ready software likely has not significantly diminished.

I see a lot of posts saying, "I vibe-coded this toy prototype in one week! Software is a commodity now," but I don't see any engineers saying, "here's how we vibe-coded this piece of production-quality software in one month, when it would have taken us a year to build it before." It seems to me like the only software whose production has been significantly accelerated is toy prototypes.

I assume it's a consequence of Amdahl's law:

> the overall performance improvement gained by optimizing a single part of a system is limited by the fraction of time that the improved part is actually used.

Toy prototypes proportionally contains a much higher amount of the type of rote greenfield scaffolding that agents are good at writing. The sticker problems of brownfield growth and robustification are absent.