If you're referring to comments on blogs in general, I have many thoughts. Back in the day, comments used to be how you connected with people and let other people find you. It also came with spam (spam plugins could only do so much).
With the rise of static site generators, most people don't have comments on their blogs now. It is something I miss though.
I’ve seen blogs that do not host comments themselves but instead automatically surface social media (usually mastodon) comments which I think is a useful technique.
But, can they?
But moderation and spam are still the hardest problems indeed.