I don't think they were "frightened" away. I think they probably just got sick of those on the left of the political spectrum constantly being referred to as communists, hard left, Corbynistas, etc., and of the level of debate being largely reliant on unsubstantiated claims, sneers and innuendo.
For the time being, I'm hanging on, though I will miss whitewave, durhamjen and - if it is true that she has left - gracesgran. And now nightowl, who I have always thought to be polite and very restrained in her comments, has said she is leaving.
Perhaps now there will be an even greater proliferation of I Hate Corbyn threads and silly cartoons and photos. Or perhaps those who are so virulent in their criticism of Labour might, for a change, start a thread listing the great positive contributions that the Conservative government has made to the wellbeing of this country and its inhabitants.