You are accusing people of doing things, yet you don't explain why, or whom you think is doing this.

The reason I ask is, and I have a lot of experience running forums, over 14 years worth.  Many NEW folks to a forum aren't really paying attention to the date, nor do they read the replies within a thread before they post, they just read the topic and have interest in it.  They have something to say, so they post.

Usually, once they become aware of the date of the thread, they feel a little embarrassed, but as staff, I gently let them know it is outdated, no longer applies, or thank them for reviving a dead thread.  Where I work, we've found some of the oldest threads posted on the net, and they go back to 93.  This particular forum site was opened, and you had to use this site to dial into the web using a coupler, goes back to 1983.  We are celebrating our 30th anniversary.

Anyway, there are always going to be people that do things to boost their post/thread count, but that isn't true for most of us.