i'd rather stay out of stuff like this, mostly because it ends up devolving into crap like the above, but this is about information loss, and that's too important to just ignore.
technically, the rules don't allow us to talk about moderators/moderation in public...but at least in this case, i think we should.
at one time, there was no ownership of threads. one could start a thread, but could not choose who could or could not post in it, or what they could say in it. if something was off topic, it could be reported and moved to a new thread, and if it was an argument or whatever, it could be reported and moved to other toxic discussions, etc.
while that can be annoying at times, it's much better than the present system, where not only is technical information lost, pattern-of-behavior information is also lost, showing how members behave towards each other, which is important in choosing who one might wish to listen to / trust.
i recall a fair bit of stuff in some of the threads referenced in this thread, that i don't really see a reason to have been removed. moved to another thread, perhaps, as not relevant to the topic at hand..but not deleted from the forum completely.
not connected directly, but relevant: it's been a while, but there have even been members that were not simply banned, but completely deleted, which removed great amounts of useful technical information from the forum (some of which i needed to use, but found is no longer there, some in my own threads, replies to me.
having been a moderator, i know it's tough to decide what to remove and what not to. no matter what you do, you're always wrong to someone.
if the "post history" feature hadn't gone away (probably during a forum upgrade?), then a moderator could simply edit out the rule-breaking material, while additionally sending a warning / pm to the poster about the specific rule being broken, and teh origianl would still exist for reference in the post history versions.
the warning and the post history would leave a written record for other moderators to be able to see patterns of behavior, so that once there's been enough problems with a particular person, the moderators as a group could decide to take further action if deemed necessary.
(btw, losing the post history lost a fair bit of info itself, because prior versions of at least some of my own posts contained technical and other info that was edited out to make the post clearer, but left in the post history for reference, and now that's all gone. other info was also lost from other members, such as those who "tantrum deleted" their stuff, but was still available in the post histories when it was needed.)