The discussions in question had gone off topic (as you note) and were essentially just a couple of the same people posting the same couple of points back and forth across 2 or 3 different threads. The mods made the decision to lock the threads and start a new thread (rather than try to prune the existing threads and direct them individually all back on-topic).
The moderators discussed whether the thread derailment, which has been the subject of numerous post reports, should be considered a Rule 11 breach and posts should be catacombed. In this case, we considered the appropriate course to be thread locking. Several threads which in our opinion had gone downhill were not redirected to new topics, although of course any board member is free to start a new topic. Others were redirected to a consolidated topic.
Board members wishing to discuss matters not on-topic to the subject are, as always, free to start threads for those discussions - although as always personal attacks are against the rules.
Feel free to review the Rules, Mission Statement, and FAQ - particularly the parts regarding staying on topic, the difference between debate and argument, avoiding flame bait, and the atmosphere of pleasant and civil discussion we try to foster here.