Indeed, looks like scientific literature in general and mathematical literature in particular are stuck in the past century. As much as I enjoy reading printed materials, I often think that using a modern computer-based approach to presenting them could prove a lot superior. And no, PDF would not cut it, even with the possibility of hyperlinking. In my view, PDF is like the idea of the horseless carriage, or, rather, of a carriage pulled by a mechanical horse - a new technology stuck in the past. Looks like the modern web browser platform, on the other hand, could provide a reasonable base on which one could build an extremely powerful "IDE" for creating and interacting with mathematical expositions.