Defined structure does not constitute quality. A commit message can be loosely structured, but be very insightful and good at communicating the nature of the change. On the flip side, one can make a very structured but confusing or non-informative commit message. I generally tend to agree with the author, conventional commits do not solve the core issue of the poor commit messages problem.
Conventional commits made it easier to generate changelogs and automate semantic version bumps. I suppose LLMs can usually do that the right way with looser structure, but in the before times it made a lot more sense, and even now is much less ambiguous