Your metaphor is slightly insane but I agree with the conclusion 100%. People who try to segregate every single line of text into a completely seperate walled off space is incredibly annoying, if for no other reason than real conversations tend to cover multiple subjects.
In Zulip, if a thread meanders with messages about a tangent, the authors/mods can choose to move those messages to a new thread (and IIRC messages with links between the two threads are created so it's easy to jump back and forth for any missing context)
