I think follow up questions to the original question are ok. However, when someone asks a question, say about culturing springtails, and someone else says, Yeah! I've got Tincs that aren't eating that I've been feeding springtails, why are they not eating...
It is a link (they usually are) but it doesn't answer the original question asked--when new people see the thread, many just see the last couple of posts and then respond, potentially taking away from the people that would respond to the original question, because they were sidetracked by the new "almost-related" question.
That being said, if the original poster likes/continues the changing of the thread, that doesn't bother me in the least.