Narrow professional or specialized forums were cleaned purposefully and deliberately, preparing space for for social networks. For this we used search engine filters (Minusinsk. Penguin). I watched the process from the inside. It took several years to understand that attempts were in vain and the result was a foregone conclusion. Similar processes have occurred with electronic libraries, but they have their own specifics, who understood it in time - survived.

Citation of former search engine worker.

I got same info from top manager who had super contact in Google. He said that Google had special secret program inside that slowly decreased ranking of any specialized forum. Forums about computer games, films, sex and similar had been excluded from the list.