The identifier can become out of date. The common argument against comments is that they're an indicator that you should factor that block out into a function with a descriptive name, but I can say for certain that method names can easily become out of date. As for doing neither, well at the end of the day you probably do want a way to summarise a block of code to the next human, rather than requiring them to read every statement

Actually, speaking as someone's who's been generally critical of the "get AI to write our PRs!" thing, having an AI attempt a quick sanity check of comments near where your edits are could maybe work well