I'm not sure why there are so many posts like this, but my best guess is that it's users either trying to rank up quickly or trying to fulfill their signature campaign commitments.
It used to be for both of the reasons you mentioned, though since the merit system started in 2018 it's really only because members want to get paid for their post. If you look at the members who are making those redundant posts (depending on which section you're in; the ANN sections might be excluded), it's almost guaranteed that the members making them are advertising something. Sometimes (like the ANN sections) it's to bump threads, but that's less often true.
And man, it used to be much worse than what you're probably seeing, although I don't know which sections you read the most. All of those posts where you could tell that the posters didn't read anything used to drive me batty. But I've used the ignore button to good effect, and my ignore list is large.
Although I'm very tempted to start, I'm still reluctant to ignore users because it feels "permanent"
I'm going to admit: I haven't read all the posts in this thread, but even the second post made mention of the fact that ignoring someone isn't permanent. With that being the case, I highly doubt Theymos is going to consider your idea when he's ignored so many other ones in the past. I appreciate you trying to make the forum better, though.