The old-school sequential form still works, BUT...it needs moderation. All the time.

I still browse similar forums, but the second someone derails a thread, or people start arguing between each others, the browsing experience turns to sh!t.

The reddit / HN format fixed this. People can discuss endlessly between themselves, without ruining the thread. People can post completely irrelevant stuff, without ruining the thread. The import stuff floats to the top, while the less important bits sink to the bottom. With the sequential form, you're pretty much forced to endure - unless mods are quick enough to remove posts.