Yeah, I'm also getting confused. Collapsible threads are enabled by defaults, unless I'm missing something. Maybe it's now about collapsed by default, i.e. you have to expand any comment thread you want to read?
> ... be able to set collapsible threads as the default
HN has collapsible threads...they are not collapsed by default...
ok, yeah, but they are collapsible by default, just not collapsed, that what confused me with that statement :D