"Destroy their argument" as a tactic is likely to get you in trouble eventually because few people are always right about being right.
The first time one of those bystanders sees you come in hot when you're wrong - or even just when they think you're wrong, since many arguments are fuzzier - you lose a lot of credibility you may never get back.
Depends on the context. On HN, sometimes I’m dead wrong, sometimes I’m spot on. I’d bet that there are people who downvoted me when I was wrong, upvoted me when I was right, and didn’t realize I was the same person. Heck, I’ve probably done that to other people on here too.
