I think that if an outright war is raging in the comments, let it run it’s course. All parties are willing participants, free to disengage at any moment.
The exceptions should be when illegal content is being shared or illegal activity is occurring (CP, doxxing, etc).
It’s always frustrating when a juicy argument gets locked because it’s “unproductive”. I was having a great time watching it unfold, both sides hurling both creative and uncreative insults, oblivious to how low they are sinking to. It’s great!
Posts should also be locked after a certain amount of time, like a year. It’s confusing to have new comments suddenly pop up on an old topic with people not realizing how old the original conversation was and saying stuff like “what do you mean xyz doesn’t have this feature? It definitely does because I’m looking right at it.” Yeah, that feature was added after the original conversation took place, then you found this old thread from a search engine (not yet a problem for Lemmy). Just let someone make a new post to keep the conversation relevant.