I recall vaguely that one of the reasons for not allowing collapsable comment trees in the past was related to the desire to make it difficult to continue comment trees, which was a good thing (more comments is generally bad, beyond a point, was the underlying philosophy).
Does this represent a departure from that philosophy, or was this never part of consideration for the feature?
Not sure I follow; introducing collapses makes it harder to extend trees (once they're collapsed), so wouldn't that argument go the other way?
In any case, we didn't think much about that concern in discussing the new features. We did (and do) worry about whether they will lessen the impact of HN's having a single communal front page and threads, now that people can hide and collapse things they don't want to see. That's something we'll try to watch out for, though I'm not sure how to measure it.
From what I understood, once you start needing to collapse threads, you're already at the threshold of "more comments are detracting from the quality," or that was the theory, anyway. I'm almost certainly misremembering.
I feel positive about this change though, I just was curious about the decision making process is all, thanks.
Does this represent a departure from that philosophy, or was this never part of consideration for the feature?