My $.02:
I noticed a similar phenomenon when I was a mental health professional and brought many of my patients to AA. (Please no AA members get your feathers in a ruffle; I'm about to say something nice. Just stick with me and you'll see.)
I observed many people going to AA regularly for years and years. I wondered why a person who hasn't had a drop of alcohol for 20+ years would need to go to an AA meeting 2x per week. It appeared to be some sort of desire to cling to a self help group they no longer needed. I listened to what they had to say and thought about it a lot.
I came to the conclusion that it was none of my business or concern. The reason is that they are doing something for themselves that they feel is helpful in staying away from a harmful thing they once succumbed to. This continued affiliation with the self help group is not harmful to them in any way. If they needed and/or wanted to continue to talk to people who went through a similar thing, who cares? Live and let live.
This forum is a self help group to assist members in healing from their past experience and in staying away from the thing that harmed them in the first place. Like AA, it also becomes an opportunity to socialize with people with whom you have something major in common with. While you are right that rehashing past harms may not be helpful, it is not necessary to do so to participate in this forum.
PS-Even during my early healing days, I never felt like I "couldn't stop thinking about JWs". I thought about them as little as possible--less than once a day. It's the screwed up perceptions of everything I was left with by the cult that I had to focus on and change so I could be normal again. Thinking about JWs was not a component of that process. (I think we agree on that point. :))