There is also an interesting phenomenon in China's internet: concentration of communities, for good or for bad. For instance, zhihu.com, the Chinese copycat of Quora has way more deeper discussion on machine learning, math, or STEM in general than Quora. On zhihu, it's easy to find the in-depth discussion of latest papers, hundreds of posts on intuition or interpretation of pretty much every STEM concepts and their historical context, dozens if not hundreds of lengthy articles that compare Raft and Paxos and ZABs and what not, all kinds of recommendations of interesting papers in top-tier conferneces, and etc. Quora, in contrast, has few such discussions because people would go to reddit, stackexchange, or some mailing list for such discussion.