Threads get closed (by certain individuals, I know who I am) only for one of two reasons.

First, if the thread mentions buying/selling/trading of commercial study materials from a third party, it gets closed. This includes STS software, NetG software, Oracle ILT books, etc.

Second, if a thread starts one of these "Me Too" type discussions where people want something sent to them, it will get closed.

I typically don't close a thread if it is offending to one person or another. That's not my beef, I could care less.