I don’t really see the creepy issue(so long as you stick to what they do on BB, or explicitly note on an external source, no doxing, even if that is often rather trivial); but I’m not certain that the task will be productive.
As best I’ve been able to tell(in my unscientific watching), the people you don’t want tend to pop up when a topic of their fixation does, spew assorted low-value chaff, and then go quiet more or less as soon as the topic that brought them stops twitching.
Unless they are a troll with a desire to plague BB specifically, rather than move around the internet following their topic, in which case the mods are going to have to sort them out; a new account tends either to be an actual person or a relatively short-term problem(sometimes not even leaving a specific thread).
The history of somebody who turns out to be a real person might be interesting, in some cases; but it’s not really anything that BBS history doesn’t capture, and it’s obviously of no defensive value.
The history of a drive-by troll might be of defensive value, except that they’ll likely have driven by before the historians have hit the scene.