There are already sites for Bitcoin and Ethereum. Now emerges new site about all of the Blockchains. I have seen such situations many times, but as far as I have seen sub-sites do not join in to more general site.
I think it is counter-productive. There are many people, who are both intrested in Bitcoin and Ethereum (for example), and larger expert number increases the probability, you will get good answer to your question.
Also this will induce cross-education between professionals and provide more understanding between users of different (but linked) technologies.