Sure, commit messages could be mandated to be "whatever an individual, community, or organization decides they should be".
That doesn't mean any of those choices is optimal in absolute terms, or even optimal for the use case of the individual, community, or organization who made the decision.
So it makes sense then to debate what the optimal choice (either absolute, or per use case) is, and this is what the article tries to do.
It would be even better if we had some kind of objective, statistical check on such claims and their pros/cons (e.g. a massive test, with control groups, well defined procedures, and such).
But debating them is also a start, and is needed. If not for anything so that each "individual, community, or organisation" has some input on their decision, and don't just arbitrary impose a format for their commit messages.