Vannevar Bush dreamed of a machine -- the memex -- where he could link together whatever he wrote and all his notes according to his associations.
Ted Nelson (he's got two homepages, one old and one more recent) dreamed of a computer writing environment where he could write like he thought. Lots of ideas "connecting in every which-way." He called it hypertext.
Both were inspired, it seems, by cognitive science in the 'sixties, which discovered the neural networks in our brains and the importance of association.
Today, we can write hypertext. Although we don't have the tools Bush or Nelson dreamed of, we have pretty good tools for quick hypertext writing.
If our brains are pleased with it. My brain often is.
And why are blogs so very sequential? As Mark once said (I think), chronology is probably the least interesting or practical way of organising blog posts. I would link to Mark's remark if I could find it...
To remedy this, I have also chosen to organise most of the notes in a large number of overview pages. I think they provide a quick way of locating a certain note, or to find related notes. Again, the idea is old: I adopted it from Landow's Victiorian Web.