I don't think most people posting on social media actually expect the politician/official to respond to a message - its more that it adds color, or perhaps anot

I don't think most people posting on social media actually expect the politician/official to respond to a message - its more that it adds color, or perhaps another view, to the official message that is posted, so that others reading the original message can (perhaps) get another side - of course it can be - and certainly is - abused, but not sure blocking people is the right solution here - anymore than it would be to allow a government official to post an op-ed piece in a newspaper, and the forbid anyone who had a different opinion from responding either in another op-ed, or in a letter-to-the-editor.