As a moderator, I typically only suggest that when a comment thread starts getting very long -- when many users (particularly on a HNQ [hot network question]) start chiming in. That can make discussion difficult to follow.
The reason we try to reduce reliance on comments:
- It's important for additional details from the OP (e.g. "I'm in the United States" or "I'm writing from the perspective of a child, not a parent") to be part of the original question/answer, so other users find that relevant information quickly and easily. I definitely want to see users asking questions to help discover and refine those details, but also want to get them into the main body, not just the fine print.
- It doesn't help the OP for dozens of people to say "I think you're to blame as the parent" or "Wow, that WAS a dumb thing your kid did" or "why are you worried about this" -- or even positive alternatives "+1 for this amazing idea" (there is voting instead!)
- Particularly when many people are commenting, it becomes a massive challenge to follow individual conversation threads, even with the @ mentions.
- Part of StackExchange's fundamental concept is that voting enables better answers to move higher, and poorly written answers to be move lower. Comments can only get upvotes.
The ways we try to reroute that enthusiasm to contribute:
- Migrating extensive discussion to dedicated chatroom, or generally suggesting Parenting Chat as an alternative. People want to talk, that's super, and there's a place for that! (And we generally prefer migration over deletion, unless migration has already occurred and people are still failing to use chat...)
- If you've got an answer, write an answer! That brings the full voting and commenting toolset into play, and avoids well-meant and often very good advice being lost in the chatter.
It's a balancing act, and I'll grant that it isn't always perfectly performed. But we try :)