In your example, those projects were not the domain of engineering. Your friends couldn't afford expertise and those projects never would have been made before. Therefore, these are net-new projects that replace nothing that came before.

This is common in technology, especially software, that improvements in efficiency make software cheaper and expands the total pool of possible software.

And, even if one of the "one button shipping" platforms (and there are many) was hooked into the agent, your friends will hit major problems that they and their AI cannot solve. Whether its tech-debt hell, a major security breach, or something else, any sufficiently complex project will require expertise. Will be a fun day when a European regulator asks a friend about their GDPR compliance and their agent is like "shrug"