They make new topics to create places for fake discussions and to fish merits and with such people, they will continue as this approach is helpful for getting their signature campaign post quota much more easily and to fish merits from other forum members including merit sources as well as to exchange merits.
Even if the aim is just to complete their weekly post, following up on their topic will make it easier for them. There is nothing wrong with posting for a signature campaign, but while at it, make meaningful contributions.
I've seen instances where people complain about a problem they're having and other users ask for clarification on the issue so they can understand how to help, but three pages later, there is no response from the OP, not one. It doesn't make any sense.
The won't get merit if it's not a quality post, so no need.
The same goes for open threads. If I open one, I look at the replies, but there are cases, like the last one I opened in the gambling section, where overnight there were six pages of replies, so after a second comment I wasn't going to stop to comment on what people had said, especially since I was asking about a personal experience.
Yeah, there are situations where it's not necessary to follow up. I can't even pretend that I will be able to read a 10 page reply of my post all at once, except I read them in batches as I received them. I might glane through, but won't be able to read all at once.
Some situations like in the gambling board or when you're just reporting a news update with the link, it may not be necessary.
It doesn't take much for people to just read a page or two of their replies and know what people are saying.