This is a mix of a question and comment.
Comment: I notice there are new "Stack Overflow-like" sites. Some that are of particular interest to me are:
But it is much more of a hassle to read through them, and furthermore to try to search for existing answers across multiple pages. The nice thing about Stack Overflow itself is that all the stuff is here, with tags and search queries. Not only do those (and other) new sites dilute Stack Overflow itself but they conflict with each other, reducing the number of persons viewing who might answer. Users must now wonder "Hm, is this a signal-processing question or a scientific computing question?"
Question: is someone at least thinking about this and estimating the number of posts that would have been on Stack Overflow that end up elsewhere? What about rate of similarly-themed questions being answered, on Stack Overflow versus another site? I guess the other sites are justified if there's some data saying that putting DSP or scientific computing questions on their own site raises their answer rate.
Even if that's the case, this will reduce the chances of me randomly answering someone's question on Stack Overflow while I'm searching for DSP and scientific computing issues!