Easy there, brother. Gotta remember that this forum is not simply an advice column, but a virtual community. There's an awesome conversational quality to many of the discussions here, and muffling that would take away at least a part of the value of this board.
One idea often spurs another, and most threads are derailed not out of a lack of courtesy or etiquette, but simply because that's how conversations flow. The benefit is that these discussions often bring up additional information that is quite useful... for example, an earlier discussion around loading 44 rounds moved into a discussion of Lee Loaders. I used the information there and asked a couple more questions in order to get myself up and running, reloading my own .44 ammo. Probably could have started a new thread, but the content I wanted was all there, except a couple of direct answers.
I do agree that the "Hey Bob" "Hey Bill" posts are tedious, and we (on the list) have been reminded by Jesse to try to avoid these. The moderators have been asked to try to redirect these types of posts back on topic, and in most cases this is happening. It's tricky though, to do this in an unobtrusive way, and as long as the meandering isn't too extreme, I think most moderators let it die out quietly, rather than put posters on the defensive and rankle feelings. It's generally harmless, if a little irritating to folks like you, who are looking at a thread for information.
It's fine to suggest, in such a thread, that the conversation come back around, by the way. There are sensitive and sensible ways of doing so, however. Most folks aren't out to sabotage the list (and I doubt anyone, in spite of jokes, is looking to build up their post count), and a gentle nudge is all they really need. If things are too off topic, suggest starting a new thread with a new topic. Or just a quick quip along the lines of, "Wasn't this thread about....?" Toss in an emoticon (smiley) to take the edge off, and you'd be amazed at how most folks will respond.
Best call? Be patient. Most people will realize what they are doing and bring it to a halt.
He has no gallery to applaud or disapprove of his conduct... Whatever his acts, they are dictated by his own conscience rather than a mob of onlookers. It is difficult to exaggerate the importance of this fact.