Do you think it's accurate to define the forums that way? Some people just use em all, I personally don't think these places/people are so one-dimensional, no matter what their ugliest opinions look like. Actually I think the problem with many subreddits/verses (in particular those about personal views like atheism/srs/fph) is the flat and incomplete view of who the users really are.
I do, yes. Hubski wants thoughtful discussion. It is run by mature responsible people and has a community (most of) who prioritize thoughtful discussion. Voat wants to be the next popular kid and will accept anything and everything without considering the consequences beyond "mah freeze peaches". One consequence being that services they relied on started ditching them. So yes, while there are some people who use all three, it is quite fair to characterize hubski as the place you recommend to good company, and voat the place you recommend to everyone else.