Hiding subthreads

I strongly agree with this. I think that deep nesting is a (often) a good signal that something has gone off-topic.
So even without the ability to hide it, nesting of subthreads is useful.
It's kind of like the kernel rationale for 8-space tabs. When something starts getting
indented too far, it's a signal that something has gone wrong.

I guess that's a vote from me to NOT go to a flat mode. If anything, it would be nice to have colored
indentation markers so you could easily return to the level of subthread that was interesting or
useful. Sometimes, on a long back and forth thread, there are other responses to early points
that are worth reading, and they are hard to find when the early messages have scrolled off the
page.