I disagree. Social media and the “contrarian” attitude they carry, especially Twitter, can help consolidating and radicalizing your opinions. You get exposed to a very toxic way to carry out conversation (especially on Twitter, where you have constant dogpiling and wannabe famous people who try to “blast” others) so that if they are the only places you discuss about certain subjects, can bring you to shift your views as well.
I am not saying this is the case for J.K. Rowling (I don’t know), but I don’t think we can immediately discard the idea that the dynamics of the medium also affected the result.