Posts do get cut out of threads sometimes and form new threads, but that's usually because the subject is interesting enough to warrant it. Otherwise the general mood of the forum is more like a bar setting with random banter, rather than informational. Other times some subjects naturally lead to other subjects that also need exploring. The thread is seemingly derailed, but then reemerges with itself with far richer content.
This does affect the newbies or people just looking for info though. That is true.
On the other hand BMs don't give people too much shit about starting new threads asking generic questions. Or asking them again in an older thread. The nature of travel and the types of questions that come up are so transitory that most info older than a few months is more or less obsolete anyway. Especially when it comes to visas, prices, etc. If you're reading posts older than 6 months you might as well be looking through the dead sea scrolls. Interesting maybe, but fuck all use 55.
That said, I think it wouldn't hurt to try and stay on track as much as possible.