I don't mean the mechanism, obviously the mod turns the key. But there does seem to be a common contributor to each thread, two now, several in the past. Sometime people are banned too. But never the common contributor. No I am not calling for a ban.
I blame train wrecks and runaway lava flows stopping traffic and forcing evacuations to avoid tragedy
You maybe on to something. They were the most active threads when locked. But then that would diminish you personally as the reason. There does seem to be something similar to silencing people with a Hugh platform when you don't like it being used. Not the same as, but the same mindset at work. But why is it at play here?
Its an effort to try to stem the tension and have people move on to another topic and hopefully cool their jets when things get too heated and personal. Sometimes when there are multiple members going at it, its hard to just ban one person from a thread, and easier to simply lock it up. I'm no mod, and not trying to speak for them, but that would be my reasoning.
I thought to someone of your knowledge this would be quite elementary. Let me walk you through it. A thread is opened on a given topic. The posts start out on topic and are productive. Then two forum members, who hold opposing views begin to banter back in forth. The banter turns to argument. The argument turns to insults. The thread has gone off topic and ventured into chaos. The mod(s) try to step in and get the posts back to the thread topic. They issue warnings. The warnings go unheeded. One of the posters argues with the mod because life isn't fair, spouts more insults. Mods issue ban(s) and close the thread.