It's about affordances. As presented, this tool streamlines copy-pasting random snippets. The easier something is, the more people do it.

Testing doesn't even enter the picture here, we're at the level of automating the stereotypical StackOverflow-driven development - except with SO, you at least get some context, there's a discussion, competing solutions, code gets some corrections. Here? You get a black-box oracle divining code snippets from function names and comments.

> the solution to that is reading all the code you commit, even though it's generated by AI

Relying on programmer discipline doesn't scale. Also, in my experience, copy-pasting a snippet and then checking it for subtle bugs is harder than just reading it, getting the gist of it, and writing it yourself.