Papers are mainly in English, and in PDF documents, which are not convenient form for on-line discussion, as the don't support commenting and discussing ideas in a central place. Researchers download papers, every-time, without seeing comments others might have written to them, and systems like researchgate.com are not supporting convenient discussion in public. Blogs generally are not treated as reputable sources, and generally don't support LaTeX markup for mathematical discussions.
So, we need some kind of solution to enable everyone (no matter in what human language, and publication), to have integrated trans-lingual, multi-threaded, multi-media discussion.
Expectedly, cross-pollination of ideas when discussing, would lead to many new developments.