You should definitely read through
I don’t mind a merge function but ideally you want to educate users before this happens – which we kind of already do, so they are ignoring it on your forum… why?
(Note that for new users they are forcibly prevented from posting more than 3 times in the same topic. So this is a behavior you can only see from regular or basic users, not new users.)
I think it’s worth talking to those users via a PM to see what’s up and also adding public moderator statements in topics reminding people how you want things to be on your forum. On some forums this might be OK, right? Depends on the norms and the culture.
That said, I generally do agree with you, it is generally a bad idea to post a lot and maximize the amount of metadata while minimizing actual content. That’s why the per-topic reminder shown in the screenshot above is part of core.