I have thought before about some topics I remember starting and how I could add to it (like the Best RPGs thread) but it would probably get locked anyway.

I agree, that's just how conversations in general work especially online. If the conversation is about a specific problem then as long as the problem is getting solved then it does not matter but a topic about the Witcher, for example, could easily springboard into being about the show, the games, the books, the Lord of the Rings, Call of Duty, why the bums outside the inn in Witcher 2 know what a potato is, etc. Lastly, it's not like a verbal discussion where you cannot turn back the clock and read the more on topic posts and reply to them.

Well as I said, the mods seem to have their "pet peeves".....one of them being that we somehow are expected to talk about one topic per thread.....like:

User 1: I love this topic...what should we talk about next? Ponies or sports maybe?
User 2: Sure, but first we must switch over to the appropriate thread.
User 1: That we must...well then: *switches to next thread to continue conversation*

I have some old threads i'd like to continue, but if I did add to them they'd likely be modded and/or locked under the new rules.