No amount of flags “nuke a post”. It may temporarily hide it until a Moderator can review the reports.
It is generally the last thing I or any Moderator wants to do, but it sometimes becomes necessary. In most cases if we notice that a thread is going off the rails a bit, we try to remove the comments that made it so. Unfortunately, what often happens is that people respond to the other folks who are derailing the thread. That makes it a bit more difficult to clean up because doing so can remove valid on topic responses in the process, riddling the thread with discussion holes.
Please keep in mind, even if we have to close a thread, the thread and feedback is still retained for our Community Management team to collect and bring to our Game Developers.
Indeed. The forum software is third party (Discourse). Blizzard oversees moderation and the like, but they are responsible for software updates. We also work with them to develop and implement desired changes. It is generally a long process, but we try to ensure that highly desired changes and quality of life improvements are prioritized.