@tsarstepan,
Threaded comments make it so that the digressions don't take over a thread, they just spark their own thread of comments that others can choose to follow or not. With the linear comments you don't get to follow one line of conversation very long, because any digression interrupts what is essentially one monolithic conversation.
Because digressions are both inevitable and often useful, the threaded view (though a less beautiful UI) is going to dramatically improve discussions here in this regard.